corundum, ruby, sapphire, inclusions.5, phenomena, star, gems

corundum, quality.10, history.1, gems

A laboratory examination of an unpolished gemstone from one of the St. Hemma jewels (11th century) of the Gurk cathedral, Carinthia, Austria, showed it to be corundum with rutile inclusions, not yellow quartz (false topaz) as labeled. The source of the stone was probably a Far Eastern locality.

diamond, inclusions, gems

synthetic corundum.7, gems, inclusions

corundum, ruby, sapphire, inclusions.5, gems

COULD they do it again? It was with this thought in m y mind that I walked into It was with this thought in my mind that I walked into the Goldsmiths' Hall on May 4th ,the opening day of the the Goldsmiths' Hall on May 4th, the opening day of the second exhibition by the Gemmological Association. I was second exhibition by the Gemmological Association. I was wondering if the Association could repeat t h e success of their first wondering if the Association could repeat the success of their first big exhibition. Had that been partially obtained because it had big exhibition. Had that been partially obtained because it had never been done on that scale before? After alll,, there wass little fresh that could be shown in gems. No startling discovery of a new variety could be expected, no novelty for the next season. In a few moments I realised that the Association had done it again and better. An exhibition of gemstones had been presented which was not only fresh butt lovelier, more interesting than the previous one. A year ago I had been fascinated by the beauty off many of the exhibits. Now I was fascinated by the beauty of thee whole exhibition. Queen Mary was an early visitor and the officers of the Association were presented to her. It was no wonder that she, with her expert knowledge of jewels and antiques, spent almost an hour looking at the exhibits. Or that she wanted to handle and feel the perfection of some of the delicate pieces of carved jade.

corundum, beryl, emerald, inclusions, synthetic beryl, emerald, gems

corundum, inclusions.5, Burma.12, Sri Lanka.12, Thailand.12, gems

beryl, emerald, synthetic beryl, emerald, inclusions, gems

corundum, inclusions.5, Sri Lanka.12, gems

gems, Arabic mineralogy, al-Biruni, rock crystal, glass

Kahle presents and translates sections of al-Bīrūnī’s eleventh-century Kitāb al-jamāhir fī maʿrifat al-jawāhir dealing with rock crystal, glass, enamel/glass fluxes (mīnā), and ruby glass (adrak), using two manuscripts and emphasizing the value of al-Bīrūnī’s account for understanding the materials and techniques represented among the Fatimid treasures. Rock crystal is described as a transparent, colorless stone prized for vessels, hardness, clarity, and resemblance to water and air; al-Bīrūnī discusses its sources, working, value, inclusions, and supposed formation, including contemporary observations and historical anecdotes concerning valuable crystal vessels. Glass is described as produced by melting quartz or sand with alkali, prolonged firing increasing its clarity and hardness; properly made colorless glass could approach rock crystal in transparency, though its greater abundance and softness reduced its value. Particularly important is al-Bīrūnī’s treatment of mīnā, explicitly described as a type of glass, softer and heavier according to its lead content. He records recipes employing finely powdered quartz or rock crystal with red lead or tin oxide, together with natron or borax-type fluxes, and gives coloring materials: lead compounds for yellow, copper compounds for green, burned brass for red, iron residues for black, manganese for wine-purple, lead white for white, burned gold for ruby color, and lapis lazuli and carnelian for violet. Kahle notes that these descriptions strongly support the interpretation of mīnā in Fatimid inventories primarily as enamel or vitreous flux. The final section discusses adrak, an ancient Alexandrian red or garnet-colored glass reportedly comparable in appearance and value to ruby and whose manufacture was said already to have been lost by the ninth century; al-Bīrūnī preserves several recipes or traditions for attempting its production, along with observations on other artificial colored materials, mosaics, and objects recovered from ancient Egyptian and Yemeni burials.