At some point, your gem collection may become large enough that you wish to sell a few pieces, or you may be ready to sell stones that you personally cut and set. There are several outlets for selling your gems, both online and in the real world.
Learn as much as you can about gemology. Besides the basic "four Cs" of cut, clarity, colour and carat weight, you will want to learn as much as possible about the stones you intend to sell. You will be able to price the gems better and answer any questions a buyer might have.
Have your gem independently certified. You may have better luck selling your stones as a result, especially online. The Gemological Institute of America (GIA) sets widely accepted standards for identifying and grading a stone (see Resources below). Look for a jeweller or appraiser who uses the GIA standards.
Start small. If you have started cutting your own gems, start by selling a piece or two to local jewellers or retailers. You will have to build a reputation before you can start selling wholesale.
Try eBay (see Resources below). You'll find a healthy amount of auctions for both rough and cut gem stones. You can also browse the auctions to help set the price for your stones.
Follow the trends if you want to make a profit. Some gems have higher demand on the market at specific times or if they have become rare. Price your gems according to these trends. If a stone becomes rare, a rough, uncut gem may become quite valuable.
Visit trade and craft shows. Not only will you be able to see what other people are selling, but you will also create contacts for selling your own gems. If you have a good amount of stones to sell, consider renting a booth.
If you plan on making a profit buying and selling gems, you will want to buy parcels (large quantities of mixed rough stones of varying quality). If you have several less valuable gem stones, you may have more luck selling them already set in jewellery.
Take care of your gem stones, whether they are cut or rough, because any flaws or damage will lower the price.