Unheated pink sapphire from Madagascar with FTIR bands at 3232 and 3185 cm–1
FTIR spectroscopy has long been used to detect heat treatment of corundum via the presence of specific absorption bands related to structurally bonded hydroxyl groups in corundum.
New discoveries in precious coral research
Since first publishing our DNA fingerprinting approach on precious corals in 2020, we have made considerable advances and discoveries in this space.
Väyrynenite of exceptional quality and size, reportedly from Nigeria
Väyrynenite is a rare phosphate mineral that was first discovered in 1935 in a granitic pegmatite near Orivesi in southern Finland.
Paraiba Tourmaline origin determination using machine learning
Since its discovery in Brazil in the late 1980s, copper-bearing Paraiba tourmaline has completely reshaped the high-end gemstone market. Famous for its electric ‘neon’ blue-to-green hues — caused by traces of copper and manganese — it has established a category of its own.
Gemmological characterisation of emeralds from Musakashi, Zambia
Zambian emeralds have been known for decades, primarily from mines along the Kafubu River in north-central Zambia (approximately 35 km south of Kitwe).
A hot issue then and now: the history and future of synthetic coloured stones
The human desire to replicate and create ‘perfect’ gemstones stems from a long history of curiosity about how these beautiful materials form.
Visit of the Letšeng diamond mine in Lesotho
In November 2025, Dr. Michael S. Krzemnicki and Dr. Michael Mintrone, Head of the Diamond Department at SSEF, were invited to visit the Letšeng diamond mine in Lesotho as part of a collaboration project. The Letšeng diamond mine is known for its large diamonds of exceptional quality and is the highest diamo
A descriptive study on as-grown and HPHT-treated CVD synthetic diamonds
The Swiss Gemmological Institute is testing more than one million colourless melee diamonds for the Swiss watch and jewellery industry on an annual basis to guarantee that no synthetic diamonds are mixed within natural melee diamond batches.
Low-temperature heating of corundum: possibilities and challenges for detection
Heat treatment is generally applied to gemstones to change and enhance their colour. Over the past few decades, it has become a very common practice for certain gem species, such as aquamarine, amethyst (resulting in citrine), copper-bearing tourmalines (Paraiba), tanzanite, and notably for any colour variety o
Unravelling the secrets of antique jewellery
Testing of antique jewellery at SSEF may provide insights which go far beyond simple gem testing. They add valuable information to the jewel, starting from its design and craftsmanship in the making, the choice of colours and qualities of gemstones, or the facet arrangement and proportions of old cutting styles