These are neat silver art rounds from India. They come in many different patterns and designs, and their size and weight varies from about 10 grams to over 50 grams. Their value varies with weight due to silver content.
The patterns we have seen are very nice. Requester Nikkabe asks about a coin with a design including the important Sikh symbol Khanda and Sikh founder Guru Nanak (shown in our secondary picture to the right). The example in our main picture (to the left) include Lakshmi (also spelled Laxmi) and Ganesha, both from Hindu traditions. The swastika, Hindu symbol of prosperity, appears on many Bombay 999 pieces. We have not been able to find Sikh designs on Bombay 999 coins, so Nikkabe's item may be somewhat rare, but we are not sure of that. The Hindu designs appear to be much more prevalent.
As to value, each piece contains some amount of silver and, in addition, there is value due to religious significance. To find silver value, first determine if the coin is pure silver, as indicated by the 999 annotation. A jeweler can help by testing the coin for purity. Then find the coin's weight in grams. Coins we have seen for sale weigh 10, 20 and 50 grams. There may be other sizes.
Next, convert the weight in grams to weight in troy ounces. There are 31.1 grams in one troy ounce, so a 20 gram pure silver coin contains 20 / 31.1 = 0.64 troy ounces. Most prices you see online, such as kitco [press here], give silver value in US dollars per troy ounce.
Find the base value (BV) of your Bombay 999 piece by multiplying its weight in troy ounces by the current silver price in dollars per troy ounce. For silver at $15 US dollars per troy ounce and a 20 gram coin, the base value is BV = 0.64 x 15 = $9.60 US dollars.
If there is no silver in the coin, the BV is zero.
Most of the time you see retail prices a few dollars above BV. In other words, you can buy these coins from dealers for about BV + $5. If you have one for sale to a dealer, the dealer will usually pay a little less than BV.