The most common diagnostic test is Moh's Scale of Hardness which every rock hound has committed to memory. From softest to hardest: 1 - Talc 2 - Gypsum 3 - Calcite 4 - Fluorite 5 - Apatite 6 - Feldspar 7 - Quartz 8 - Topaz 9 - Corundum 10 Diamond fingernail is 2 1/2 steel pen knife blade is 5 1/2 window glass is 5 1/2

so how do you use your household gadgets to figure the moh's rating? do you take your steel pen knife blade and poke it into your precious rock?

got another question: you know how you can go into shops and find amethyst in the rough? what makes it different (beside the obvious) from what is sold? how can they sell it for cheap but a polished and worked stone is much more expensive? makes me wonder if those bits and pieces of "amethyst" are real or not.

Last question first...most of the price of a stone is in the cutting and polishing (and mounting). I have a huge slab of magnificent amethysts my son gave me for my Birthday. It was 3 figures, but still inecpensive condisering the size of it! Those bits are real indeed, and I have all sorts of them from tumble-polished beads in long ropes to solitaires set in rings. Amethyst is abundant and beautiful - no one would bother to fake it. For years I carried a streak plate (unglazed porcelain) and a penny (2 1/2) and knife and small window glass plus a known pieve of quartz when I went into the field. It is to check if the red thingy sparkling at you from the sand is glass or garnet.

As to your question about finding out the hardness of household things, these have been well ascertained that I am giving you. Ideally you would have a specimen of each of the stones in the Moh's Scale to go into the field with you, but I find that a chunk of quarts is sufficient. Anything harder than quarts (and can scratch it) deserves much closer scrutiny since they are all from the precious stones category. Your streak plate is used to see the color of the mark left by streaking the specimen over th gritty surface. Hematite - a dark silver stone used in jewellry - leaves a very evident orange streak since it is an oxide of iron (thus the rust-colored streak.)

interesting!! there's a diamond crater in arkansas. i wonder if i should pack up my gear and take a dig....

Mrs Clinton wore a pheasant-egg-sized champagne diamond found in Arkansas to the first inaugural ball - loaned to her by someone who was a loyal supporter. If that sized gems are wandering around, think what might still be in the ground!

you know how you can go into shops and find amethyst in the rough? what makes it different (beside the obvious) from what is sold? how can they sell it for cheap but a polished and worked stone is much more expensive? makes me wonder if those bits and pieces of "amethyst" are real or not. The rough stuff is not deemed "gem-quality." Usually because of color or lack of clarity. You can get bargeloads of the stuff in S. American for cheap and use it as livingroom art sculpture. It is real, but not of good enough quality to polish and cut and sell for jewelry. Usually bookend size is good enough for most people though.

interesting...i always wondered that and thought maybe others did too, thanks for the help!

Minor mistake in terminology. All unpolished gems are called "rough." BTW, the lesser quality stuff may also be polished into cabochon form (nonfaceted) and set or strung into beads.

Indeed, and we need to get that into precious stones too...!