Specific Gravity Kit

If you get something like a jiffy bag and have the coin at a 45 degree angle, then let your magnet slide down it should slide down slowly on silver. Too fast it's not, and if it sticks it's not. The jiffy bag or something similar i'd say use to avoid scratching.

Now with specific gravity, you can make a home-made version. You need scales, cut a small plastic bottle in half and a piece of string-like sewing cotton, not parcel string. Weigh the coin and cotton together and note the weight, the cotton shouldn't be that heavy at all. Then fill the half plastic bottle with water and but it on the scales, tear the weight/zero it. Then tie the cotton around your coin. Place the coin into the water, so it is fully submersed and not touching any sides what so ever. Take note of the weight. Then divide the first weight by the second weight and you should have the specific gravity weight.

Note: with the cotton you could also weigh the coin alone, and with cottn then find the mean weight for usage.

Silver specific gravity weight:10.492 (10.4-10.53)999, 90% 10.33,
Gold:19.32
Platinum:21.37
Copper:8.93
Lead:11.24
Nickel:8.02
Tin:7.29

Some of these may differ given the purity variance, but the above are for pure/fine 999.
Hope this helps :D.

This is a simple device with a list of the equipment. Cool.