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May 5, 2016

3 Characteristics of a Quality Gem

Local Gemologist and Jeweler, Kevin Castro of Castro and Company, was the guest speaker at the May meeting of Southern Utah Rock Club. Meeting the 1st Wednesday of each month at the Cedar City Aquatic Center, Mr. Castro educated members on Diamonds and Gemstones.

Kevin Castro
Kevin Castro


His 60 minute talk gave members a chance to learn the history of diamond mining and the industry and as well as information on the largest diamonds ever mined. His 25+ years of training and experience gives him the opportunity to share many stories and a wonderful historic perspective on the diamond industry.


Mr. Castro shared the three characteristics of a quality gem
• Beauty
• Rarity
• Durability

Beauty was the depth and the quality of the stone. Whether faceted or shaped, the stone should show depth and light.

For rarity, there are hundreds of gems and minerals in the world, but only 100 are deemed Gem Quality and have any rarity. Diamonds are rare, only in the sense of the number the diamond cartel chooses to release each year in order to maintain prices.

Durability speaks to the hardness of the stone and the methods of stabilization. Turquoise is a soft material and needs stabilization or a backing material to be durable. Diamonds, on the other hand, are the hardest material known to man. Their durability is so high that diamonds that are not gem quality are used in hundreds of other manufacturing processes. Even lapidarists use diamond wheels to cut and polish their stones.

Perhaps the best question of the night came from student member Cole, who asked how to recognize a real diamond. Mr. Castro gave three ways individuals could most probably identify a real diamond – all require the use of either a 10 power loop or a microscope.

Membership in the Rock Club is open to anyone interested in rocks. The club meets the 1st Wednesday of every month (except December) and takes an outing to identify and collect rocks from public and private lands each month.

The last trip was this past weekend to Tonopah, Nevada to “hunt” in the Royston Turquoise Mine. A fee collecting site, many wonderful specimens and gem quality rocks were found by the 18 members that attended. Watch for next week’s article on Nevada’s “Gemfield”.

Current membership stands at around 150 and each meeting there is time for members to “show and tell”. Many members are signed up for the Southern Utah Rock Club Facebook Page.
View the page at: https://www.facebook.com/groups/1491676831116962.

If you’d like to see Mr. Castro’s work and visit his retail outlet visit his webpage at: http://castrojewelers.com/

Until next time – – –