Message: Hi, Surbhi. My mother in law bought about 50 scarab bracelets/necklaces/rings, etc. I am having trouble distinguishing between glass, plastic, stone, gold silver, brass. I know you answered a question about this topic about a year ago. Any extra advice?
1. Look into the loupe
2. Use a diamond tester
3. Get the jewel appraised or certified
4. Get a certificate from the seller
The ground rule for distinguishing the difference between diamond and any other material is to look into it through at least 10 times magnification.
The most important distinction between a natural and man made stone is the difference in the impurities or inclusions inside a stone. You will look for 'bubbles' inside the plastic / glass or natural looking feather like or small black inclusions inside a diamond.
On the surface, what you are looking for is the 'sharp' clean edges of a diamond vs that of plastic. Even the slightest of wear and tear will cause rounding of edges and corners in plastic.
As compared to glass, you will be looking for 'single refraction' inside a diamond. You have to look inside the stone and rocking / swaying it gently to move the 'lines' created by the facets on the bottom of the stone. If you see 'double' lines for each edge of a facet then it is DEFINITELY not a diamond. If you see single lines then you would have to look for further indications as to whether or not the clear stone is a diamond.
Besides this, the weight of a diamond vs the weight of a plastic piece is very different. The diamond is definitely much heavier than either plastic or glass. If you can get a total weight of the stones in carat and then measure each stone (if feasible) in mm then you can refer to any carat-mm chart available online. This is slightly impractical but not really out of the question.
Once you have ruled out that the stone is neither glass nor plastic, then come the real challenge will be to figure out if the stone is synthetic moissanite or synthetic diamond or some other very close imitation of a natural. To rule out any of those, you would probably look for more or less the same... differences in impurities or else take it to someone more experience for an opinion.
To figure out whether or not the metal is gold or not, you would first and foremost weigh it. If the weight tallies with that of the karat of gold that was mentioned, then you are safer and can go on to the next step of using a karatmeter or a gold pen.
Unfortunately, without prior experience, it is not a very easy thing to judge whether the stones are real or not, but if you are a keen observer and sit with a bunch of real stones as well as fake or imitation stones, and a loupe, you will be able to eventually figure out the differences and also the beauty of what makes a stone a 'diamond' vs any other.
All the best, for any further questions or comments, please write to firstname.lastname@example.org