Best way to test metals

Discussion in 'Bullion Investing' started by wcoins, Jan 15, 2018.

  1. Coin Talk User

    Coin Talk User New Member

    Diamond testers were built to separate CZs from diamonds, since they look nearly the same. CZ has very low thermal conductivity while diamond has very high conductivity. Sapphire and moissanite have high conductivity too. Occasionally sapphire of any color may test as diamond [topaz too] but their optical properties are much lower than diamond so the tester would know the difference and disregard. Find a trained gemologist if you want to be sure of a stone's identity. Sometimes jewelers don't know.
     
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  3. -jeffB

    -jeffB Greshams LEO Supporter

    I think moissanite is distinguished from diamond only on its refractive index. Many years ago I came across a widget in a scrap bin that I believe was an assembly for a moissanite tester. The big moissanite producer (Charles and Colvard, formerly C3, spun out of Cree) was local, and I think they made testers to give out to jewelers or gem distributors. It looked like it was purely optical.
     
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  4. Coin Talk User

    Coin Talk User New Member

    The refractive index is not the only difference. Moissanite is slightly electrically conductive while diamond usually is not. Testers are helpful but the eye is better. Moissanite is doubly refractive and often has inclusions of a specific type. Diamonds are singly refractive. If you know what to look for, you don't need a tester.
     
  5. abuckmaster147

    abuckmaster147 Well-Known Member

    Being ignorant here, but what about size or weight? if you have a 1/2k can or will they be dif size?
     
  6. -jeffB

    -jeffB Greshams LEO Supporter

    Moissanite is less dense than diamond, but I think the difference is less than ten percent. That would make it difficult to measure -- if two stones are cut the same, and have the same weight, the moissanite would be only about 3% larger in each dimension.

    The funny thing is, moissanite is superior to diamond in appearance -- its refractive index and dispersion are both significantly higher, giving it more brilliance and fire -- and it's nearly as hard (durable). It's even fire-resistant. But it's not backed by tradition and De Beers, so none of that really matters. :rolleyes:
     
  7. Coin Talk User

    Coin Talk User New Member

    Diamond is much harder than moissanite. After years of wear, the diamond is likely to look brand new while moissanite and others will be worn at the facet edges and scratched on the table. There is a current misconception that diamonds are found everywhere and are wildly over-valued. The market for 3+ carat diamonds is quite good - the wealthy have not lost their desire for them. Back to talking about coins now.
     
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