Happy hour with soda and lime: glass imitating coral
Recently, a necklace was submitted to SSEF for coral testing. Already a first microscopic inspection revealed that this item in fact consisted of numerous tiny glass beads, visually imitating coral very well (e.g. corallium rubrum). The most obvious microscopic feature was the presence of air bubbles in these g
Novel Coral-ID method used on samples seized by swiss customs
In 2022, an international research group led by scientists from the Swiss Gemmological Institute SSEF and the University of Zurich’s Institute of Forensic Medicine (IRM) reported a breakthrough in precious coral jewellery traceability, through the use of a novel forensically validated genetic technique called
Saltwater pearl with barium
Recently, the SSEF received a button-shaped pearl of 7.5 ct for testing. Based on X-ray radiography and a UV-Vis-NIR reflectance spectrum, the pearl was easily identified as a saltwater natural pearl from the species Pinctada margaritifera.
Cultured pearl with unconventional bead material
Recently, we received a round pearl for testing which exhibited an excellent surface quality and a remarkable size of 24 mm in diameter. Interestingly, its weight of 60 ct was rather low for such a pearl (resulting in a calculated specific gravity of approx. 1.61 instead of 2.715 considered standard for a pearl
Assembled blisters and shells used to imitate pearls
Since historic times, natural pearls have been treasured and considered symbols of wealth and beauty. When harvesting (natural) pearls, one may find not only a pearl inside a shell, but also blister pearls and quite often blisters. A pearl has grown completely wrapped in a pearl sac in the mollusc, whereas a bl
Pearls & diamonds: a royal selection
The SSEF is known worldwide as a leading authority in gem testing, and as such we have the great pleasure to scientifically analyse some of the most prestigious and important jewellery before it is offered up for auction or in private sales. Apart from testing the gem materials in such jewellery, we are often i
Queen Mary pearl: age dating & DNA fingerprinting
Similar to gemstones which are re-polished over time and thus need an updated SSEF report, we also occasionally receive pearls a second or third time for a new report, for example when the pearl is set in a new jewellery design. This is specifically the case when a pearl is important and/or of historical proven
The value of cultured pearls: evolution and current trends
Pearls are often reported as the oldest valuable gem known to humankind, and have been collected for at least 8,500 years (Ainis, et al., 2019). Natural pearls are accidental formations in wild oysters or mussels, and have been considered to be one of the most precious gems in many cultures (Kunz & Stevenson, 1
The allure of back opals
Opal comes from the Sanskrit upala and the Latin opalus, meaning “precious stone”. The Roman naturalist Pliny the Elder (A.D. 23/24 – 79) wrote that: “In the opal you will see the refulgent fire of the carbuncle (red gems), the glorious purple of amethyst, and the sea green of the emerald, and all these
New and additional criteria to detect low-t heated corundum
Heat treatment of ruby, sapphire and other colour varieties of corundum is one of the main issues for the gem trade. As such, detecting such treatment is a major task of gemmological laboratories issuing gemstone reports. Unfortunately, and especially lately, the detection of such heating is not always straight