Wednesday, 26 December 2018

Royal Spinel - Balas Ruby

Spinel is the magnesium aluminium member of the spinel group. It has the formula MgAl2O4. Balas ruby is an old name for a red variety.

After the 18th century the word ruby was only used for the red gem variety of corundum and the word spinel became used. "Balas" is derived from Balascia, the ancient name for Badakhshan. The Badakshan Province was for centuries the main source for red and pink spinels.
Spinel is most famous for its deep red variety that closely resembles ruby. The two gemstones can be very difficult to distinguish. Until the late 19th century, there was no distinction made between ruby and red spinel, as they look identical and are found in the same localities. Many famous old "rubies" were discovered to be spinel.

Mining in Afghanistan has a history over 2,000 years as gold, silver and precious stones were routinely mined. Afghanistan's ruby/spinel mines were mentioned in the writings of many early travellers.
The Badakhshan mines were of great importance during the period from 1000–1900 AD. They were the source of many of the finest early red spinels in gem collections around the world, such as those in the crown jewels of Iran, the collection in Istanbul's Topkapi, Russia's Kremlin and Diamond Fund, and England's Tower of London.

Imperial State Crown

During the Soviet occupation, mining of all Afghan gem and mineral deposits was controlled by the state. However, since many mines lay in inaccessible areas, such mining became an important source of income for the rebels.
In the late 1980s, large reddish spinels were reported from the Pamir mountains of what is now Tajikistan. One 532 carat rough yielded cut gems of 146.43 and 27.81 carats. Ruby was also reported in eastern Tajikistan, near the border with China, in the early 1980s.

Political difficulties and rugged terrain make Afghanistan a difficult country to explore, and Tajikistan is no better.
The Hope Diamond had a counterpart in the collection it was in — the Hope Spinel.

Both belonged at one time to powerful London banker Henry Philip Hope, who died in 1839. The 45.52-carat Hope Diamond now resides in the National Museum of Natural History at the Smithsonian, while the 50.13-carat spinel headlined Bonhams’ Fine Jewelry sale in London on September 24, 2015. It was expected to fetch between £150,000 and £200,000. It made £962,500

Sunday, 23 December 2018

Design by Roberto Coin

Founded in Vicenza in 1977, Roberto Coin was first established by its eponymous creator to produce for internationally acclaimed jewelry brands.

The Roberto Coin brand was introduced in 1996 and within six years had reached the upper echelons of the jewelry world, ranking third internationally and first in Italy. The Roberto Coin brand is mix of centuries-old Italian craftsmanship and modern design techniques. Each and every piece of Roberto Coin jewelry is unique and handcrafted, from the delicate to the bold; all are exquisite.

The signature of Roberto Coin is the use of rubies and rubellite. Roberto Coin has 8 boutiques worldwide.

Michigan's state gem : Chlorastrolite

Michigan's state gem is found in one place -- and you won't find it anywhere else. Chlorastrolite is a variety of the mineral pumpellyite, and it is exclusively found along the Keweenaw Peninsula and throughout the Isle Royale archipelago -- Michigan's most remote national park.

Commonly called Isle Royale Greenstone, ancient lava flows cooled into basalt.
Within that basalt were small pockets of empty space left behind from gasses in the lava -- and that is where chlorastrolite eventually formed. Chlorastrolite is difficult to find because of its size. Large pieces are extremely rare.

Saturday, 22 December 2018

Cutting Lesedi la Rona

Graff has unveiled the first of more than 60 diamonds it plans to polish from the 1,109-carat rough Lesedi La Rona stone it purchased last year from Lucara for $53 million. The Lesedi La Rona was the second-largest rough diamond in history, second only to the 3,106-carat Cullinan. The polished diamonds will range from under a carat to more than 100 carats, mounted as solitaire rings, earrings and pendants.
Lesedi La Rona means “our light” in Botswana's Tswana language. It took master diamond cutters and gemologists more than a year of analysis, cutting and polishing before attaining the first 67 stones.