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Semi Precious Stone Grading


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im looking to get different stones to use for inlay stuff like calcite, fluorite, azurite, malachite, turquoise, chrysocolla. im looking to buy it it as cheap as possible so i need the poorest quality because i will end up crushing it up for inlay so i dont need a realy nice pattern or realy strong matrix. but i dont know how stone is valued. some people have it by the gram, others sell it by the string, and still others sell it by the inch. and is there a grade of stone like there is for wood?


if someone knows of a web page that will explain stone buyin to me or can tell me please let me know. or if you know of a company that would sell what im looking for. which is poor strength stone of small sizes since im not going to carve or use for jewlary so small chips are fine. just going to break them up into small pieces.

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this web site might be what i need but i still dont understand how they value stones. when i buy wood cabinet grade select and better is like 90 percent clear good wood. and common 3 is is the worst of building material that is sold with 40 percent knot free wood. so when i buy stones and i need some thing i can crush up for the visual texture and the color im guessing i want to get equivalent of common 3 since i dont need large stones or something im going to make into jewlary. plus how do they sell it because i keep finding strings of chips, LB, oz, grams, karats i have even seen people sell it layed out in a row and sell it by the inch. is there some kind of standard that every mine or disributer sells it by?

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http://www.durangosilver.com/turquoisegrades.htm found this and using this as a guide on buying turquoise.


all the turquoise on fire mountain says dyed and treated from what i have figure out that means that it is treated with resin to strengthen it and dyed to make the color stand out because it probably grade d or chaulk since im planing on crushing it i dont care if it has been dyed or it has resin in it as long as i can crush it up and the color stays true. has anyone ever carved into one of these stones does the color stay on the surface or is it colored thorugh out?

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Dan you just landed right into my specialty! I really depends on the type of stone that is being graded. for an example when you grade gold you grade it by its purity based on the properties it is made up on. in the case of stones you grade it by its color, luster, form, and hardness. diamonds are priced by carats, so are rubies, topaz, beryl, opals, sapphires, and a couple of others. remember semi-precious stones are not cheap. Other more common stones are sold by size, purity, and uniqueness of the specimen being sold.


heres something that may help.


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richard then maybe you can give me a some pointers because the wiki page did not help much just said its graded by 13 different instatutions. im looking for the cheapest stones as long as it has a steady color. perhaps you can tell me the best way to buy these stones since im just after the colors because im going to break it up into small pieces. im looking at......




red jasper

sponge coral red

red flower stone

yellow marble



black onyx


red calcite

golden fluorite











how would you buy these i have goten them all on fire mountain for small chips 16-34 inch chains for most are around a doller a few are bit more.

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Personally i think your choices are very well picked based on the many colors and variations they come in. Natural specimens and tumbled specimens of each of the individuals would give you the best chances at great natural colors and grades they come in.

Here three personal favorite sites i have visited quite often and i am pleased with the stock and the honesty of these sites( a rarity nowadays)




I will post later after a bit of research and browsing about the individuals

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as for steady colors Fire mountain is cheap yet very well done. I am not sure whether they dish out naturals or posers, but it is a very good site for purchasing at dirt low prices. based on what i have seen about them is either carrying low grade stones, or are being very generous to their customers. the stones look genuine and great, but in terms of heat treating i think they do that quite often lol. if you are not familiar with heat treating then here it is plain and simple. Heat treating basically heats up the stones and the impurities inside them, causing the impurities and the host to attain a better color and pattern than its original and natural form did

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seems like they have a wide mix or natural and imiatation. i have no problem using both as long as i can count on the color being true after its smashed up. that way i can buy stones and break them up and have a visual texture when its glued in here is a video of the process if you inturested



i had been leary of buying the mixed tumbled stones thinking they might be howlite.


inturesting about the heat treating. last week i read they have been doing heat treating for a long time like way way back in history.

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  • 2 weeks later...

I might be able to help a little, The strength of a stone is graded on the Mohs hardness scale, Talc being #1 and up to Diamond at #10. you can check each of the stones you listed on Wiki page and they will have the number as part of the definition, stones rarely vary much and trying to crush #7 and up require special equipment. Another thing to think on is that most of the silica based stones like Chrysoprase of Amethys get their color from minerals like Nickel and Iron and if did manage to crush them the oxegen in the air will bind to them a change them to nickel-oxide and Iron-Oxide changing the color to bland. I think the only one i saw that could take a good crushing and keep it's coor was Lapis, get the best quality you can find, the purity makes it easier to powder up. good luck and use a good sledge or rock hammer, #5 and #6 can often splinter the metal from construction type hammers.

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  • 1 month later...

An alternative to using stone for inlaying is to use "enamell powder". Whilst I have not done a lot of inlaying, I found the powder ( just carve a groove in the pattern you want, spinkle in the powder, leaving it proud of the carved item and dribble in suprglue) leave it over night and clean it up with diamond burrs and polish. It seems that the enamell is ground up glass and extreemly hard when set. heaps of colours available. and can be mixed to alter the colours. I also mix with clear glass to add sparkle.

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  • 3 weeks later...

thanks colin ill check it out. do you know how hard those are? maybe some kind of compareson. regular sand paper is 9 on the moh scale.

Hi Dan, I've tried using various "fillers" for inlaying,but found the enamelling powder matches my favourite stone (argillite) for hardness. Argillite is around 4.5 on the scale. Sort of around marble . I don't know about grades that are available I use some of the left over powders from past hobbies and am happy with the result. Can be mixed with stone grindings as well. Cheers Colin

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