Sapphires are considered precious gemstones, along with rubies, emeralds, and diamonds. This is not surprising, considering the amazing range of colours these gems can show, as well as being the third hardest mineral on the Mohs scale.
What is an optical phenomenon? Plainly put, this term embodies the result of the way light interacts with the crystalline structure, inclusions, and/or internal structure of a gemstone. It is, in essence, the reflection, diffraction, absorption, and/or diffusion of that light. Without even knowing, we encounter these phenomena on a daily basis, whether in opal, moonstone, alexandrite, or cat’s eye chrysoberyl—that said, one should be careful not to confuse optical property, such as dispersion in a diamond, with optical phenomena.
Field gemmology and travelling to mines directly is a great learning opportunity: you can see the sites and the people you want to work with, observe the conditions, build relationships and contacts, and meet amazing individuals with infinite stories they can share with you over a good drink.
Much to the delight of those in attendance, this year’s Tucson gem shows were as exciting and joyful as ever. As with every February, industry members came together in the desert to marvel at the colourful gemstones and oddities lining the streets.
Most working in the industry are aware sapphires are routinely treated to increase their marketability. What many dealers, manufacturers, and retailers may not be aware of, however, is a relatively new treatment used to beautify unattractive sapphire: high pressure, high temperature (HPHT).
Rubies in North America are so rare that these stones used to be only available to collectors; however, thanks to a new mine in southwestern Greenland, North American rubies are now being sold in jewellery stores.