What is Iris agate? Cause of Spectral colors when viewed in transmitted light? What is the best cutting orientation and Quality Factors?

  Iris agate is agate whose thin section shows spectral colours when viewed in transmitted light. These colours are not thin-film colours such as those of precious opal. Specimens of iris agate were observed in 1933 by Fred S. Young.

Iris agate

 In 1935 when Fred S. Young and Dr. H. C. Dake first showed the author thin slices of iris or rainbow agate, the display of colours recalled the similar appearance of a diffraction grating. Microscopical examination soon confirmed the opinion that a periodic banded structure existed in the agate, and revealed interesting correlations with the chalcedony's structure and variations in fineness and regularity. No satisfactory explanation of the formation of this regularly banded structure has yet been devised although the theory proposed by Hedges may apply in a general way.

Iris agate from Mexico

                                             Iris agate from Indonesia 

   

 OCCURRENCE: South Africa, USA, Indonesia

Best Cutting Orientation of Iris agate and Best Quality Factors:    In order to produce the best play of colours the slice of iris agate must he cut so that the thin layers, whose edges are the lines of the diffraction grating.

 Fig. 1 Iris agate 9,600 lines to the inch. 370X.

 As shown in Figs. 1 to 5, will be at. right angles to the polished surface. The slice will show the brightest colours if it is thin (1 mm. or less) because the absorbing and scattering effect of any milkiness will then be at a minimum. If the line spacing is uniform, as in Fig. 1, a very thin slice will show primary colours even if the layers in the agate are somewhat inclined to the polished or lacquered surface, although the slice may have to be tilted to correct for the inclination. A specimen which shows primary colours in very thin section may show only pastel colours if it is cut too thick. If the line spacing is not quite uniform only pastel colours may be seen, and if it is very irregular only a chatoyance will be observed.

      A single band of uniform spacing will show only one colour for a given position but any adjacent band of uniform but the different spacing will give a different colour for the same position because a fine spacing will diffract anyone wavelength through a larger angle than a coarser grating. In addition, the finer gratings separate the colours from each other more than do the coarser gratings, consequently they give purer, more saturated colours.

 Fig. 2. Iris agate between crossed nicols showing single lines and turtleback. 80X.

   LINES PER INCH

      The fineness of structure observed in iris agates ranges from about fifteen thousand to as few as four hundred lines per inch. Figure 1 shows; a specimen having about 10,000 lines per inch. Part of Fig. 2 shows only 400 lines per inch. Finer and coarser spacings may exist in some agates but any spacing in this range will show the grating effect. A grating of only 100 lines per inch will show diffraction colours but they will be so close to the illuminating beam that they will be difficult to see. Gratings as fine as 30,000 lines per inch have been observed by the author in some crystalline organic materials.

      A variation in spacing of the lines such as shown in Figs. 2 and 3 may possibly be caused by changes in the rate of crystallization of the chalcedony, either because changes in temperature occurred or because of the composition (concentration) of the solution (perhaps a gel) varied, or both. It is also possible that the coarse spacing shown in Fig. 2 may be of the ordinary successive deposition type with the grating structure starting, but failing to continue in each of the broad layers which happen to be fairly uniform in thickness. The fact that the needles seem to be continuous across several layers may be explained in the same way phantom lines in single crystals are explained. 

Fig. 3. Iris agate showing spacing differences and change of direction at the grain boundary. 80X

CORRELATION OF GRATING LINES AND CRYSTALS

  The lines in iris agate are always at right angles to the length of the needle-like crystals of chalcedony. Figure 1 shows an unusually straight set of lines but even these are slightly wavy because the crystals are not all exactly parallel to each other. It should be pointed out also that the waves run along with the layers within the specimen at right angles to the cut surface, but the amplitude of the waves is small and a thin slice will give good colour in spite of the front to back waviness. Figure 2 shows lines that curve because the crystals have grown in radiating clusters. This structure is sometimes termed "turtleback" or "spherulitic." Figure 3 shows a relatively coarse structure of varying fineness and also reveals that the banding is continuous across adjacent groups of crystals in spite of abrupt changes in direction. Figure 4 is the same specimen as Fig. 1 but seen between crossed nicols and at only 80X. The irregular, ragged black bands indicate changes in polarization colours of the chalcedony but do not correlate with the grating structure. (See Fig. 5.) Such coarse patterns appear to the unaided eye as a woven cloth such as burlap.

Fig. 4. Iris agate between crossed nicols. 80X.

 Fig. 5. A. Iris agate between crossed nicols showing start of narrow band where crystal size changes. 80X. B. Start of the grating band seen in A. 200X.

Figure 5A shows a band of iris starting where short, relatively jumbled crystals change to long, nearly parallel crystals. Figure 5B shows the start of the grating band at higher magnification. In most specimens the iris bands show a higher order of polarization colour arid more uniform orientation than adjacent bands which do not show the iris grating structure; however, these differences are not always noticeable. The band of the iris which begins where the crystal size changes (Fig. 5) becomes finer where a band of cloudy material extends across the field but becomes coarser again beyond the cloudy zone. This cloudy material may be opal which can exist between the crystals of chalcedony.⁶ Colloidally dispersed impurities such as the brown ferric hydroxide type of gelatinous appearing "moss" often occur in the bands between the iris bands, but very little such coloured impurity is ever-present in the iris bands themselves. In any case, it appears that the chalcedony in which the grating structure is present must be quite pure and sufficiently free from porosity to prevent much diffusion of iron stain or dyes between the crystals.

      The observations above indicate that the grating lines must have been formed while the crystals were growing but it is the author's opinion. that the manner of their deposition is not the same as the irregular deposition of the ordinary bands in agate. Organic materials such as cholesteryl acetate melted under a cover glass have been observed crystallizing rapidly in rhythmically banded structures which produce a display of rainbow colours just as does iris agate. Probably a similar process proceeding at a slower rate is responsible for the grating structure in iris agate.

Sources: American Mineralogist, Volume 37, pages 578-587, 1952 by FRANCIS T. JONES, 244 Trinity Ave., Berkeley 8, California.

                          Colibrí al atardecer (Hummingbird at sunset)

A Rare coral Found neat the Galapagos Islands.

A rare and beautiful type of Coral found near the Galapagos Islands, Ecuador.

The world’s top five diamond mining countries by volume of production, report 22 March,2020

Although the world’s first diamond deposits are believed to have formed 900 million years ago, the first stones were found in India in the fourth century BC.

Despite being best known for use in jewellery — such as rings and necklaces — because of their durability and lustre, 80% of mined diamonds are used for research and industrial applications. Because they’re the hardest material on Earth, diamonds are often used to cut, grind, or drill other tough materials.

Around 147 million carats were mined in 2018, with a worldwide market value estimated at $76bn, according to data analyst Statista.

1. Russia

Home to arguably the richest and largest diamond resources in the world, Russia tops the list with more than 12 open-pit mines. With mining starting in 1947, Russia now tops the world’s diamond production hierarchy. It is also the world’s largest exporter of rough diamonds by volume. The country’s major miner is a group of companies called ALROSA, which produces the majority of Russia’s diamond output.

Russia mined 38 to 39 million carats in 2014 (out of which ALROSA mined 36.2 million carats), while 2018 saw this increase to 43 million carats. Most of the country’s mining deposits and activities occur in the Siberian region of Yakutia.

Latest assessments indicate Russia’s diamond resources to be 973 million carats out of which the known reserves are 608 million carats.

Recently, a double-diamond (a diamond within a diamond, aptly nicknamed Matryoshka, like the Russian doll within a doll) was discovered by miners at ALROSA’s Yakutia site, at the Nyurba division. This double diamond, estimated to be 800 million years old, was claimed to be the first of its kind.

 

2. Botswana

Africa’s top diamond producer, Botswana sits second in this global list. Since the 1870s, most gem-quality stones have been mined in Africa and, in 2017, the value of diamond exports from African countries in the global market was valued at $9.65bn.

Diamond exploration started in Botswana in the 1950s, with mining officially launching in 1971. Some of the world’s highest-yielding mines were unearthed in Botswana by the mid-1980s. The African country’s diamonds are generally larger than those mined in Russia and boast a better quality. They also constitute about 25% of Botswana’s GDP and 60% of its exports.

In terms of value, Botswana leads the list of the world’s top diamond-producing countries, despite being the second by volume. In 2013 alone, 23.2 million carats worth $3.63 billion were mined in Botswana. The Karowe Diamond Mine, owned by Canada’s Lucara Diamond Corp, recently produced the world’s second-biggest gem at 1,758 carats.

Botswana houses seven top-class mines, out of which Orapa and Jwaneng,  are the world’s two most productive diamond mines. Jwaneng alone produces an average of 10 million carats per annum.

3. Democratic Republic of Congo

The Democratic Republic of Congo (DRC) comes third in the line of diamond mining countries by volume, although the informal sector (and not mining companies) is responsible for most of its production. It is estimated that about 700,000 artisanal miners belonging to this sector operate the country’s mines in search of the precious stone. The joint venture between the DRC government and Belgian company Sibeka, Miniere de Bakwange (MIBA), is the only commercial diamond mining company in the country. MIBA produced about nine million carats in 2000. Approximately one-third of DRC’s diamonds are marketed by De Beers, which has a 20% stake in Sibeka.

Although production has declined in recent years due to constant political turmoil, DRC holds the potential for more diamond production. Until now, mining has taken place only on a small scale with just a small area being explored. DRC’s 2018 tally of diamonds mined was assessed to be nearly 16.4 million carats, worth about $136.1 million. This figure increased to about 19 million carats in 2019.

 

4. Australia

Fourth in the world when it comes to diamond production, Australia began to mine the stones commercially from 1981.

Since 1983, Australia’s largest diamond mine, Argyle, an open-pit mine, has been producing a steady stream of natural coloured diamonds at the rate of more than 12 million carats per year. Located in the East Kimberley region of Western Australia, the Rio Tinto-owned Argyle’s diamonds made up the initial source of the country’s up-and-coming diamond industry. However, only about 5% of its production is gem-quality output. In 2013, Rio Tinto transformed Argyle into an underground mine to extend its life up to 2020, at least.

There are two other mines in Australia: The now shut down Kimberley Diamonds-owned Ellendale, and the Merlin Diamonds Ltd’s Merlin mine (both in the Northern Territory). The former, which produced yellow diamonds, is waiting for a new operator to restart it. The latter produces high-value, high-clarity white diamonds and it was here, in 2003, that Australia’s largest diamond weighing 104.73 carats was discovered.

With the depletion of deposits and few discoveries, diamond production Down Under has seen a sharp fall. The present output of 14.2 million carats is expected to fall to 134.7 thousand carats by 2021.

5. Canada

Mining in Canada began in 1998 after evidence of diamond-bearing kimberlite pipes was found in the Northwest Territories in 1991. Ekati, owned by Dominion Diamonds, was the first operational mine in Canada. This paved the way for more mines, which soon made Canada the world’s fifth-biggest diamond mining country. The country’s other three active mines are Diavik (owned by a Rio Tinto Subsidiary), Snap Lake and Victor. The latter two are De Beers-operated mines.

In 2013, Canada extracted 10.6 million carats of diamonds worth $1.9 billion, which increased to 23 million carats worth $2.7 billion in 2018.

Apart from these four, other mines are in various stages of development, such as the Renard-owned Stornoway Diamonds and GahchoKué of De Beers.

Difficult mining conditions due to frigid and remote locations, or the ores petering out, have seen some of Canada’s mines being shut down.

Canadian diamonds are more popular with buyers because they are not classed “blood diamonds”, like their African counterparts where environmental protection regulations and worker interests are often severely compromised.

The Pink Diamond of Iran " The Great Table Diamond"

The Great Table diamond was first reported by gem merchant Tavernier in 1642.

In Tavernier’s list of the “largest and finest diamonds and rubies seen by him in Europe and Asia,” the Great Table appears third.

Of it he remarks: “It is a stone which weighs 176 1/8 mangelins, which make 242 5/16 of our (old) carats. When in Golconda, in the year 1642, I was shown this stone, and it is the largest diamond I have seen in India in the hands of dealers. The owner allowed me to make a casting of it, which I sent to Surat to two of my friends, calling their attention to the beauty of the stone and to its price, which was 500,000 rupees. I received a commission from them to offer 400,000 rupees for it, but it was impossible to come to terms at this price.”

Tavernier’s accompanying illustration shows the Great Table to be table-cut, so that it may be easily recognised should it again come to light in India or elsewhere but a popular theory suggests the diamond has been broken up and has not been seen by any European expert since.

Drawing of the Great Table diamond, by Tavernier in 1676

The Great Table is said to have been in the possession of the first Mogul emperor of India, from whom they descended to Mohammed Shah. 

When the latter was defeated by Persia’s Nadir Shah during the sacking of Delhi in 1739, he surrendered all his chief valuables, including the diamonds and the well-known Peacock Throne.

After Nadir’s assassination in 1741, the gem was inherited by his grandson, Shah Rokh. 

Later, it descended in succession to Mirza-Alam Khan Khozeime and then to Mohammed Hassan Khan Qajar. Finally, it came into the possession of Lotf-Ali Khan Zand, who was defeated by Aga Mohammed Khan Khan Qajar.

Aga Mohammed was succeeded by his grandson Fath Ali Shah in 1797, who was both a collector and connoisseur of gems and whose name is engraved on one side of the great diamond.

The Great Table is next mentioned by Sir Harford Brydges in 1791, a British diplomat hired by the Shah of Persia to sell some diamonds to raise funds so he could wage war on a neighbour. 

At this time, Brydges reported that the stone was exactly as Tavernier had described. This is the last known reference to the stone’s sighting.

Summary 

Weight: 242.31 carats
Dimensions: 59.42mm x 33.51mm x 13.25mm (estimated)
Colour: Pale pink
Rough weight: Unknown; assumed to be semi-polished crystal
Origin: Golconda, India
Date found: Unknown; probably early 1600s
Current location: Cut into the Dary-i-noor and the Nir-Ul-ain in the early 1800s

Worldwide Gemological Laboratories Contact Information Accredited Gem Appraisers Address : 730 Sansom St., Philadelphia, PA-19106, USA. Telephone : 215-873 Email : info@gemappraisers.com Website : http://www.gemappraisers.com AGT Gem Laboratory Address : Tokyo: 5-15-14 Ueno, Taito-ku, Tokyo Building 2F CY Okachimachi Osaka: Minamisenba 2-5-8, Chuo-ku, Osaka Building community Nagahori Telephone : Tokyo: (+81)03-3834-6586 / Osaka: (+81)06-6266-8601 Email : info@agt.jp Website : http://www.agt.jp/ AGT Gem Laboratory is a website that provides services related to the inspection and grading of diamonds and other gemstones. They issue reports to ensure the safety of the jewelry industry and consumers. They also offer seminars to educate people about gemstones. The website includes information about their services, reports, seminars, and knowledge about gemstones. They have a membership program, and their contact information is available on the website. The website is easy to navigate, and the important information is presented clearly. AIGS-Asian Institute of Gemological Sciences Address : AIGS Laboratory, 919/1 Silmon Road, Jewelry Trade Center, 6th Floor, Bangrak, Bangkok 10500, Thailand. Telephone : 662-267-4325, 662-267-4327 Email : info@aigslaboratory.com Website : http://www.aigsthailand.com The AIGS website is all about gemology, which is the study of gemstones. They have a school where you can take courses to become a gemologist, and they also have a lab where they test and report on gemstones. The website has information about the school's courses, how to enroll, and frequently asked questions. They also have information about the lab's reports, how to become a VIP member, and overseas offices. The website has a gem dictionary and information about different types of gemstones. You can also read about the experiences of students who have attended the school. The website has contact information for their offices in Thailand, Japan, and China. Overall, the website is a great resource for anyone interested in gemology or looking to become a gemologist. American Gemological Laboratories Address: 580 Fifth Avenue #706, New York, NY 10036 Telephone: (212) 704-0727 Email: agl@aglgemlab.com Website: http://www.aglgemlab.com/ American Gem Society Laboratories (AGSL) Address : 8917 West Sahara Avenue, Las Vegas, Nevada 89117, US. Telephone : (702) 233-6120 Email : agslab@lvcm.com Website : http://www.agslab.com AnchorCert - Address : PO Box 151 Newhall Street, Birmingham, B3 1SB Telephone : 0871 423 7922 Email : gem@theassayoffice.co.uk Website : http://www.anchorcert.co.uk/ Bharrat Gem Testing Lab Address : 42/16, Motilal street, T. Nagar, Chennai -17, Tamil Nadu. Telephone : 24338725 Email : bgtl@scientist.com Chandigarh Gem. Lab Address : Booth No.4289, Sector 22-D, Chandigarh 160022, India. Telephone : 0172-2726333, 9855080808, 9855133391 Email : cglindia@yahoo.com CISGEM Address : 30, Viale Achille Papa, Milano (MI), 20149, ITALY Telephone : +39 02 8515 5250 Telephone (Labs): +39 02 8515 5324 Fax: +39 02 8515 5258 Email : [url]info.cisgem@mi.camcom.it[/url] Website :http://www.cisgem.it Diamond and Gem Laboratories of America Address : 415 Sargon Way, Suite B, Horsham, PA-19044, USA. Telephone : 215-443-7900 Email : datlas@dglaservices.com Website : http://www.dglaservices.com Emil Gem Laboratory Address : 6th Floor ASIA GEMS TRADE CENTER BUILDING 242-250 MAHESAK ROAD, SURAWONGSE, BANGRAK BANGKOK 10500, THAILAND Telephone : 0-2234-8872, 0-2237-1928, 08-4772-5775 (Thai), 08-1912-8208 (English/Japanes) Email : info@emil.co.th, micky@emil.co.th Website : http://www.emil.co.th EGL USA- European Gemological Laboratory-Los Angeles Address : 550 South Hill, Suite 840, Los Angeles, CA 90013, USA. Telephone : 877-893-8593, 213-534-2224 Email : egl@eglusa.com Website : http://www.eglusa.com EGL USA- European Gemological Laboratory-New York Address : 6 west 48th Street, New York, NY 10036, USA. Telephone : 212-730-7380, 212-842-5180 Email : egl@eglusa.com Website : http://www.eglusa.com E G Lab Emteem Gem Laboratory, Address:24/4A, Al Fassy Mawatha Chinafort, Beruwala,Sri Lanka Phone 0094 342279278 Email: mtmharis@sltnet.lk Website: emteemgemlab.lk European Gemological Laboratories-Mumbai Address : 520, Parekh Market, 39,Kennedy Bridge, Mumbai-400004, Maharashtra, India. Telephone : 022-65207186 Email : contact@eglindia.biz Website : http://www.eglindia.biz European Gemological Laboratory-Toronto Address : 55 Queen Street E., Suite 500, Toronto, ON M5C 1 R6, Canada. Telephone : 416-368-1200 Email : egl@eglusa.com Website : http://www.eglusa.com European Gemological Laboratory-Vancouver Address : United Kingdom Building, 409 Granville Street, #456 Vancouver, BC V6C 1T2, Canada. Telephone : 604-630-0464, 604-630-0465 Email : egl@eglusa.com Website : http://www.eglusa.com Gem Scan Laboratories Address : 6A, Unity House, 2nd floor, Opera House, Opp to Panchratna building, Mumbai - 400004, Maharashtra, India. Telephone : 022-23673612/84 Email : info@gslabsindia.com Website : http://www.gslaboratories.com Gem Scan Laboratories Address : Prashanth Real Gold Tower, 9th Floor, North Usman Road, Chennai - 600017, Tamil Nadu, India. Telephone : Email : info@gslabsindia.com Website : http://www.gslaboratories.com Gem Scan Laboratories -Canada Address : Gem Scan Laboratories Inc., 27 Queen Street E., Suite 406, Toronto, Ontario, Canada M5C 2M6. Telephone : (416) 868-6656, 1-877-868-6656 Email : info@gemscan.com Website : http://www.gemscan.com Gemlab Address : Laboratory for Gemstone analysis and reports, Mr. Thomas Hainschwang, Gewerbestrasse 3, FL-9496, Balzers, Principality of Liechtenstein. Telephone : +423 262 2464, +423 373 2243 Email : laboratory@gemlab.net Website : http://www.gemlab.net Gemmological Institute of India Address : 503, Sukh Sagar Building, N.S.Patkar Marg, Opera House, Mumbai-400007,Maharshtra, India. Telephone : 022-66519030, 022-23612769 Email : gemforum@giionline.com Website : http://www.giionline.com Gemological Science International - India Address : Gem Experience Pvt.Ltd., 4th Floor, Sangrajka House, Beside IndusInd Bank, Lamington Road, Opera House, Mumbai 400004. Telephone : 022-67470099, 022-66101683 Email : india@gemscience.net Website : http://www.gsiindia.net Gems & Gemological Institute of Pakistan (GGIP)-Peshawar. Address: Suite # 209, 1st Floor, Benevolent Fund Building, Sadder Road, Peshawar - Khyber Pakhtoonkhwa – Pakistan Phone: (+92-91) 9213303, 9213196, 9213197 Fax: (+92-91) 9213198 , Email: ggipeshawar@yahoo.com Website: http://www.ggip.com.pk/ German Gemmological Association (DgemG) Address : Prof.-Schlossmacher-Str.1, D-55743 Idar-Oberstein, Germany. Telephone : 49(0)6781/50840, 49(0)6781/508419 Email : info@dgemg.com Website : http://www.dgemg.com GHI India Pvt. Ltd. Address : 5C, 5th Floor, Mehta Mahal, 15 Mathew Road, Opera House, Mumbai-400004,Maharashtra, India. Telephone : 022-23610270, 022-23610271 Email : svabanya@yahoo.com,daryl0801@yahoo.co.uk GIA- New York Address : 580 5th Avenue, Suite 200, New York, New York-10036, USA. Telephone : 800-366-8519, 212-944-5900, 212-575-3095 Email : labservice@gia.edu Website : http://www.gia.edu GIA-Carlsbad Address : 5355 Armada Drive, Carlsbad, California-92008-4699, USA. Telephone : 760-603-4500, 760-603-1814. Email : labservice@gia.edu Website : http://www.gia.edu GIA-Thailand Address : 10th Floor, U-Chu-Liang Building, 968 Rama IV Road, Bangkok-10500, Thailand. Telephone : +66-2-632-4090, +66-2-632-4096 Email : info@giathai.net Website : http://www.giathailand.com Gemacyt Laboratorio Gemológico Address : 15, Siena St. 1º C 28027 - Madrid - Spain Telephone : 34 917 000 935 Fax : 34 913 194 000 Email : http://gemacyt-lab.com/contacto.php Website : http://gemacyt-lab.com Gemological Center “GEMEXIM” Ltd. Address : Please supply Telephone : +7 (495) 280 04 37, +7 (495) 280 04 38 Email : gemexim@yandex.ru Website : http://www.gigia.ru (GRS)Gemresearch Swiss Lab -Switzerland Address : GRS Gemresearch Swiss Lab Ltd., P.O. Box 4028, 6002 Lucerne, Switzerland. Telephone : 41 (41) 210-31-31, 41 (41) 210-31-34 Email : adolf@peretti.ch Website : http://www.gemresearch.ch GRS Gemresearch Swisslab -Thailand Address : Jewelry Trade Center, Room 919/257, 20th Floor, North Tower, Silom Road, Bangrak 10500, Thailand. Telephone : (66+2)237-5898, 630-0112 Email : adolf@peretti.ch Website : http://www.gemresearch.ch GRS Lanka (Pvt.) Ltd. Address : Galle Road 471 2/1, Colombo -3, Srilanka. Telephone : 94-11-2583326, 94-11-2582493 Email : adolf@peretti.ch Website : http://www.gemresearch.ch GS Gem Scan Laboratories Pvt. Ltd. Address : 347, Panchratna, Opera House, Mumbai 400 004, Maharashtra, India. Telephone : 022-23673612/13 Email : info@gslabsindia.com Website : http://www.gemscan.com Gübelin Gem Lab Ltd. Address : Maihofstrasse 102, 6006 Lucerne, Switerland. Telephone : (+ 41) 41-4291717, 41-4291734 Email : info@gubelingemlab.ch Website : http://www.gubelinlab.com Hanmi Gemological Institute Lab (HGI) Address : 3F, 35-1 , Bongik-dong, Jongrlo-gu, Seoul, 11()-390, korea Telephone : 02-3672- 2800~2 Email : hanmilab@hanmilab.co.kr Website : http://hanmilab.co.kr/english/ HKD Diamond Laboratories (Canada) Address : 21 Dundas Square, Suite 807, Toronto, Ontario Canada M5B 1B7. Telephone : 416-368-7266, 416-368-8527 Email : info@hkdlab.com Website : http://www.hkdlab.com HKD Diamond Laboratories (Canada) Pvt. Ltd.-India Address : 543, Panchratna Building, Opera House, Mumbai-400004, Maharashtra, India. Telephone : 022-23683336/7 Email : info@hkdlab.com Website : http://www.hkdlab.com IGC Universal Gemological Laboratory (I) Pvt. Ltd.-India Address : Sunville Bldg, Paper mill lane, Opp- Greens Restaurant, Lamington Road, Mumbai-400064, Mahrashtra, India. Telephone : 022-23882535/7311 Email : india@igc-labs.com Website : http://www.igc-gem.com IGC- Universal Gemological Laboratories-Israel Address : Diamond Exchange, Maccabi Building Suite 1956, 1 Jabotinsky St., Ramat Gan, Israel-52520. Telephone : 97237514782, 97236132651 Email : igc@igc-labs.com Website : http://www.igc-gem.com IGC- Universal Gemological Laboratories-Rusia Address : Smolnaya str, 12, office 250, Moscow , Russia-125493 Telephone : +7 495 4523376, +7 495 4522278 Email : igc-gem@mail.ru Website : http://www.igc-gem.com IGI- Belgium Address : IGI Belgium - World Head Office, Schupstraat 1, 2018 Antwerp, Belgium. Telephone : 32-3-231.68.45 Email : info@igiworldwide.com Website : http://www.igiworldwide.com International Diamond Laboratories-Dubai Address : GOLD&DIAMOND PARK, Building 3, 1st Floor, Sheikh Zayed Road, Dubai, UAE. Telephone : +971 4 3807999 Email : info@diamondlab.org Website : http://www.diamondlab.org IGI- India Address : International Gemmological Institute (I) Pvt Ltd, 404, Mani Mahal, 11/21, Mathew Road, Opera House, Mumbai-400004, Mahrashtra, India. Telephone : 022-23672550, 022- 23642861 Email : india@igiworldwide.com Website : http://www.igiworldwide.com IGI Istituto Gemmologico Italiano Address : 1, Piazza San Sepolcro, Milano (MI), 20123 ITALY Telephone : +39 02 805 049 92 Fax: +39 02 805 057 65 Email : [url]laboratorio@igi.it[/url] Website : http://www.igi.it Independent Gemological Laboratories- USA Address : 21 West 38th Street, New York, NY 10018, USA. Telephone : 212-382 0008, 212-382 0009 Email : customerservice@dia-lab.com Website : http://www.dia-lab.com Independent Gemological Laboratories-Mumbai Address : 2B Jain Tower, 17 Mathew Road, Opera House, Mumbai-400004, Maharashtra, India. Telephone : 022-56842533 Email : india@dia-lab.com Website : http://www.dia-lab.com Instituto Gemológico Español Address : C/Alenza 1, 28003-Madrid, Spain. Telephone : +34 914-414-300 Email : info@ige.org Website : http://www.ige.org/ International Diamond Laboratories-Belgium Address : Hoveniersstraat 27, 2018 Antwerp, Belgium. Telephone : +32 3 232 62 08, +32 3 232 63 28 Email : antwerp@diamondlab.org Website : http://www.diamondlab.org International Diamond Laboratories-Dubai Address : Jewellery & Gemplex, Building 3, 1st Floor, Sheikh Zayed Road, Jebel Ali, Dubai, UAE. Telephone : +971 4 3688674, +971 4 3688675 Email : info@diamondlab.org Website : http://www.diamondlab.org International Gemological laboratories and Institute Address : C-25, Veer Savarkar Marg, Lajpat Nagar II, New Delhi-110024. Telephone : 011-29811824 011-46546225 Email : info@igli.in Website : http://www.igli.in/ Lotus Gemology Co. Ltd. Address : Silom 19 Building Suite 413, 4th Floor 45/1 Soi 19, Silom Rd Bangkok, 10500, Thailand Telephone : +66 (0)2 117 3616 Email : info@lotusgemology.com Website : http://www.lotusgemology.com MSU Gemological Center Address : Gemological Center, Department of Geology, Moscow University Main Building, leninskie Gory, GSP-2, Moscow, Russia-119992. Telephone : +7 095 939 4973, +7 095 932 8894 Email : gemology@geol.msu.ru Website : http://www.gemology.ru SSEF Swiss Gemmological Institute Address : Falknerstrasse 9, CH-4001 Basel, Switzerland. Telephone : +41 61 262 0640, +41 61 262 0641 Email : gemlab@ssef.ch Website : http://www.ssef.ch Stone Group Labs Email : bear@stonegrouplabs.com Website : http://www.stonegrouplabs.com/Welcome.html Swedish Gem Lab Email: info@gemlab.se Website: https://gemlab.se/ The Gem and Jewelry Institute of Thailand Address : Gemmological Research and Testing Building, Faculty of Science, Chulalongkorn University, Phayathai Road, Patumwan, Bangkok 10330, Thailand. Telephone : (622)218-5470-4, 652-5252 Email : jewelry@git.or.th Website : http://www.git.ot.th/eng/eng_index.htm Zitco Gem Testing Lab Address : Kolcutta, West Bengal. Telephone : 09373314622 Email : zitco@gemtestlab.com Website : http://www.zitco.com

Quartz

Quartz is the second-most abundant mineral in the Earth’s continental crust, after feldspar. It is made up of a continuous framework of SiO₄ silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO₂. There are many different varieties of quartz, several of which are semi-precious gemstones. Throughout the world, varieties of quartz have been since antiquity the most commonly used minerals in the making of jewellery and hardstone carvings.

The quartz group includes a number of different species/varieties. There are two categories crystalline quartz and cryptocrystalline quartz (chalcedony).

Source: en.wikipedia.org/wiki/Quartz

Cause of Color: Rose Quartz: Charge transfer reaction (Ti⁴⁺ and Fe²⁺) as a result of irradiation.

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Chemical Composition : 

Silica (Silicon Dioxide) SiO₂

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Crystal System / Forms : 

Trigonal System

• Prismatic with pyramidal terminations (rhombohedron, trapezohedron, trigonal, pyramid)
• Horizontal striations on the prism face, rhomb shaped on the rhombohedral face, ‘V’ shaped markings in twinned crystals.
• Most quartz is commonly twinned.
• Types of twinning include Dauphine, Brazil and Japan law twinning.
• Exhibits both contact and interpenetrant twinning.

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Cuts & Uses : 

Facetted cuts, cabochon, carvings, beads, etc.

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Dispersion : 0.013

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Hardness : 7

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Lustre : Vitreous.

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Magnification : 

Liquid and two-phase, colour zoning, negative crystals, zebra-stripe fingerprints (structural), crystal inclusions, green fuchsite mica flakes/platelets in aventurine quartz, rutile/tourmaline needles in sagenitic quartz. Brazil law twinning is seen in natural quartz.

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Optic Character : 

Anisotropic, D.R.; Uniaxial positive. May exhibit a bull’s eye optic figure (quartz rotates the plane of polarisation parallel to the c-axis).

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Pleochroism: Dichroism - weak to moderate.

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Refractive Index / Birefringence : 

1.544 – 1.553 / 0.009. Range: 1.535 – 1.560

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Sources : 

Brazil, India, South Africa, Namibia, Madagascar, Zambia, Sri Lanka.

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Specific Tests :

• Piezoelectric: develops an electric charge when pressure is applied.
• Pyroelectricity: develops an electrical charge when heated.
• Diasterism in star variety (star visible in reflected and transmitted light).

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Spectrum : 

Green aventurine: bands at 682nm, 649nm

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Synthesis : 

Hydrothermal process:

• Colours – colourless, pink, blue, green, etc.
• Identification: type of twinning, seed plate, breadcrumb inclusions, Raman / infra-red spectroscopy.

Corundum

Name:	corundum
	Class:	Oxide/Hydroxides
	Chemistry:	Al2O3
	Color(s):	red (ruby), blue (sapphire), gray, black, yellow, purple, (just about all colors) streak: white
	Hardness:	9	SpecGrav:	3.9 - 4.1
	Fracture:	tough	Cleavage:	none
	Crystal:	hexagonal
	Envronment:	in pegmatites, in contact metamorphics, and in other metamorphic terrains.
	Association:
	Locals:	|Burma | China | Sri Lanka | NC, Mo., USA |
	Misc:	The name comes from the ancient Sanskrit, ³kuruvinda² meaning ³ruby². It is derived from the Tamil ³kuruntam², which also came from the Sanskrit. Do to its hardness it is also used as an abrasive.

C

Easy Ways To Clean Jewelry At Home

1. Vinegar

What You Will Need

• ¼ cup vinegar
• 2 tbsp baking soda
• Warm water

Processing Time

5-10 minutes

Process

• Mix all the ingredients in a bowl to make a thick paste.
• With an old but soft toothbrush, rub the paste all over your diamond ring or jewelry. Continue to do this for a few minutes.
• Rinse it with tap water and pat it dry.
• Alternatively, you could soak the jewelry in vinegar for about 5 minutes before you go ahead and clean with the paste.

2. Baking Soda

What You Will Need

• 2 tbsp baking soda
• Warm water

Processing Time

5-10 minutes

Process

• Take about 2 tbsp of baking soda and add a little water to it to make a thick paste.
• You can replace water with white vinegar (optional).
• With an old toothbrush or a scrub, apply this paste to the jewelry you plan to clean. Scrub carefully.
• You will start to see the dullness diminish and your jewelry piece begin to shine.
• Rinse it with water and repeat this procedure if needed.
• Avoid using them on anything with enamel, gemstones or pearls.

3. Toothpaste

What You Will Need

• Toothpaste
• Cotton cloth or toothbrush
• Fresh towel

Processing Time

5 minutes

Process

• Toothpaste is one of the most inexpensive, easy, and effective ways of cleaning your junk or silver jewelry.
• With a soft cotton pad, cloth or a toothbrush, rub a little paste all over and wipe it thoroughly.
• Give it one last rub with a damp or a fresh towel.

4. Hydrogen Peroxide

What You Will Need

Hydrogen peroxide

Processing Time

5 minutes

Process

• Pour a cap full of hydrogen peroxide in a cup. Make sure the ringgets fully immersed in it.
• The dust will react with the hydrogen peroxide and start to make bubbles.
• Remove the ring from the liquid. After a while, dip it back in and leave it there for another minute or so.
• Take it out and rinse with regular water. Your ring will be shinier than ever.

Note: Hydrogen peroxide helps remove all the stubborn grime and grit that has settled on your diamond rings over the years.

5. Alcohol – Vodka, Tequila, Beer

What You Will Need

• Alcoholic drinks like vodka, tequila or beer
• Bowl
• Soft cloth

Processing Time

5 minutes

Process

Dip a soft cloth in vodka, beer or tequila and rub it onyour jewelry thoroughly.
You will start to see that your jewelry will start to shine. These come in handy for more things than one, if you know what I mean.

6. Ammonia

What You Will Need

• 1 cup warm water
• ½ cup ammonia
• Paper or cloth towel

Processing Time

15-20 minutes

Process

• Take ½ cup of ammonia and mix it with a cup of warm water – put your diamond, silver or gold jewelry in this.
  Let it be submerged in the liquid for 15-20 minutes.
• Rinse it with water, and let it dry on a cloth or a paper towel.

7. Tamarind Paste

What You Will Need

• Tamarind paste
• Toothbrush
• Paper towel or cloth

Processing Time

15-20 minutes

Process

• Tamarind is acidic and helps remove the black pigment on your silver items and jewelry. Plus, it is the most natural way of cleaning your silver items.
• Soak a lemon sized portion of tamarind in a little water for about 15 minutes and mash it into a paste.
• Scrub your items with a brush using the tamarind paste. You can do this as often as you like to keep your silver shining and brand new.

8. Soapnuts

What You Will Need

• Fistful of soapnuts
• Warm or regular water
• Bowl
• Scrub or toothbrush

Processing Time

20 minutes

Process

• Take a handful of soap nuts and soak them in a cup of water for about 15 minutes.
• Now, extract the soapy liquid from it and submerge your gold or silver jewelry in it for some time.
• Scrub the items and wash them with tap water.
• Let them dry, then clean them with a paper towel.

9. Aluminum Foil

What You Will Need

• Aluminum foil
• Laundry detergent liquid or powder/ baking soda
• Pot of boiling water
• Toothbrush
• Paper towel or a cloth to dry

Processing Time

30 minutes

Process

• Line a steel bowl with aluminum foil and fill it up with water.
• Let it come to a boil.
• Now, add laundry detergent powder or baking soda and turn the stove off.
• You could alternatively just use shredded aluminum foil and throw it in the boiling water.
• Add your jewelry pieces to this and leave them for a couple of minutes.
• Take them out and brush them using a scrub or an old toothbrush.
• Dry them on a paper towel.

10. Ketchup

What You Will Need

• 2 tbsp ketchup
• Soft cloth

Processing Time

10 minutes

Process

• Dip a soft cloth or a brush in ketchup and clean the items with it.
• Rinse it with tap water.
• Repeat, if needed.

Note: Ketchup might sound a little bizarre, but it works because it is highly acidic and helps getting rid of all the grit and grime build up on your silver jewelry.

11. Boiling Water

What You Will Need

• Pot of boiling water
• Laundry detergent (optional)
• A dry towel

Processing Time

30 minutes

Process

• Cleaning your jewelry with boiling water is the safest option.
• Turn the stove off. (Add a little detergent of any kind to the bowl if you want.)
• Soak the jewelry for about 15-20 minutes.
• Scrub them and clean with fresh water.

12. Lemon Juice

What You Will Need

• 1 tbsp lemon juice
• ½ cup water
• Scrub or toothbrush
• Paper towel

Processing Time

Overnight

Process

Squeeze out 1 tbsp of lemon juice and add it to ½ cup of water. For best results, soak your jewelry in this solution overnight and wash them the next morning. If you are in a hurry, scrub your jewelry with this liquid for a few minutes and rinse it with tap water.

13. Dish washing Liquid

What You Will Need

• Dish washing liquid
• Warm water

Processing Time

30-35 minutes

Process

• Add a few drops of the dish washing liquid to a bowl of warm water.
• Add your silver, gold or diamond jewelry to this.
• Let them soak in the water for 30 minutes or so.
• Rinse them with cold water.
• Pat them dry with a paper towel or a soft cloth.

14. Alka Seltzer

What You Will Need

• Alka Seltzer
• Warm water
• Dry cloth

Processing Time

30 minutes

Process

• Alka Seltzer cleans your diamond rings in minutes and makes them sparkle like new.
• Just add a couple of Alka Seltzer tablets in a bowl of warm water. Put the jewelry in the bowl.
• Let them stay there for about 20-25 minutes.
• Take them out and clean with a dry cloth.

You can do all of these in no time, and they are so easy to do! So sorry, you have no excuses. There’s nothing more satisfying than to see things getting clean and shining. Take it up as your weekend project and let us know if any of these easy ways to clean jewelry at home worked for you by dropping in a message in the comment section below.