Grandidierite and other Rare Gemstones at SSEF
We would like to present three minerals which were tested in the past few months at SSEF and which at least partially made headlines in the news for collectors and aficionados of such gemmological rarities.
New Emeralds from Afghanistan
Emeralds from Afghanistan are well known in the trade for their beauty and size, and are considered a historic source of fine emeralds. Despite the political turmoil of recent decades, these mines have recently produced again a number of gems of outstanding quality and size, as we could observe at SSEF during t
Field Trip to Paraiba Tourmaline Mines in Brazil
In October 2017, a team of gemmologists from the SSEF had the privilege to visit some Paraiba tourmaline mines in Brazil to get impressions about mining procedures, sorting, cutting and trading activity in the states of Paraiba and Rio Grande do Norte.
Exceptional Spessartine Garnets
first published in Facette 21 (February 2014) In 2013, the SSEF tested a number of very outstanding spessartine garnets. This manganese dominated member of the garnet group commonly shows a highly attractive and vivid orange colour and is thus also known and described in the trade as ‘Mandarin garnet&rs
Padparadscha-like fancy sapphires with unstable colours
Fancy sapphires found in recent years in Madagascar brought to light colour stability issues. Some of these samples show an unstable colour, shifting from pinkish orange (padparadscha-like) to pink after a fading test are reported. We report on research findings on these stones and explain the causes and implic
GemTOF Analyses of Sapphires from Madagascar and Kashmir
In the beginning of 2017, gem testing laboratories started to receive cut stones from a new area for gem analysis and issuing reports. As stated in a trade-alert by SSEF in early 2017, some of this new sapphire material may resemble internal features of Kashmir blue sapphires, therefore careful microscopic inve
New Beads in Cultured Pearls
by Dr. Laurent E. Cartier, first published in Facette 21 (February 2014) We were presented with samples of a new type of pearl product from French Polynesia by a pearl trader during the 2012 BaselWorld show. These cultured pearls had unusual shapes, came in large sizes (up to 23 mm) and were characterised by
Corroded Pearls
by SSEF, first published in Facette 20 (January 2013) Although pearls, as organic gems, are commonly less stable than polished gemstones, we don’t often see pearls with obvious features of surface damage as a result of unfortunate care. A few months ago, however, we received for testing a very spectacular ca
Exceptional Colour Change Garnets Showing the Usambara Effect
by Dr. M.S. Krzemnicki, first published in Facette 21 (February 2014) Colour change, also known as“alexandrite effect” has been studied extensively since it was first described in 1831 for alexandrite (chromium-bearing variety of chrysoberyl) from Russia (von Pott, 1842). Since then, numerous minerals or g