Gemology Hub | Gemstone & Mineral Identification Guides

Radiocarbon research adds a time-related question to pearl testing: when did the sampled pearl material form? This can help investigate historical claims, but age and natural-versus-cultured formation are different questions. A recent pearl can be either natural or cultured. How the historical research worked SSEF’s 2013 article describes collaboration with ETH Zurich. A small amount of pearl material was removed and measured using accelerator mass spectrometry. The method used carbon-isotope information, including the increase linked to twentieth-century atmospheric nuclear testing. Unlike an X-ray image, this procedure consumes a sample. The article describes an early research project, so its sampling amount and service availability should not be assumed to apply to every current test. Why the environment matters Marine reservoir effects can influence the apparent age. Freshwater pearls may be especially difficult because older carbon from limestone can enter the growing pearl...

The outside of a pearl can look convincing while its centre holds the most useful identification clues. X-ray microtomography, often called micro-CT, helps laboratories examine these hidden structures in three dimensions without cutting the pearl open. From a flat image to virtual slices A conventional radiograph projects internal features onto a flat image. Structures can overlap in that view. Micro-CT uses multiple X-ray views to reconstruct the interior, allowing the analyst to inspect virtual sections in different directions. SSEF’s 2009 article describes how this approach helped investigate pearl growth features. It highlights difficult beadless cultured pearls, for which a clearer view of the central region can be particularly useful. What can the images show? Cavities, fissures and growth structures can become easier to understand when viewed from several angles. The analyst can ask whether a line belongs to one cavity or whether several different features overlap. This p...

Natural and cultured pearls both form inside molluscs. The key difference is whether people started the process. An imitation pearl is a manufactured lookalike. These three names describe different things, even when the beads look similar in a necklace. How a pearl begins A natural pearl forms without human intervention. A cultured pearl develops after a farming procedure, often involving a small piece of mantle tissue. That tissue can form a pearl sac, which deposits pearl material. Some cultured pearls grow around an inserted bead; others grow without one. Nacre, also called mother-of-pearl, contains very thin mineral layers. Their interaction with light helps create a pearl’s attractive sheen. A beadless cultured pearl is still cultured: the absence of a bead does not remove the human role in its formation. Why appearance is not enough Roundness, colour and lustre do not reliably tell you whether a pearl is natural or cultured. SSEF’s 2004 article explains the importance of e...