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
Sapphires from Ambatondrazaka, Madagascar
Madagascar, an island of many gem treasures, saw in recent months another ‘sapphire rush’ after the discovery of a new gem deposit about 35 km east of the small town of Ambatondrazaka.
Sapphire from Andranondambo, Madagascar
first published in Facette 22 (February 2016) In 2016, the SSEF received a sapphire of exceptional quality and size for testing (Figure 1). The sapphire of 33 ct was characterised by a saturated blue colour, – poetically also known as royal blue and a highly attractive velvety appearance due to submi