This depends on a number of things, such as how much it weighs and what the current price of 10K gold is.
Men's Class Rings usually weigh between 12 and 22 grams, so the first thing that you need to do is to weigh yours. It is possible to get scales that use these tiny measurements.
This can change on a day to day basis so you will need to check what the price is. This is particularly true if you are planning on selling the ring because naturally you want to get the best possible price for it that you can. Here is a site that may be useful to you: http://www.goldprice.org/scrap-gold-price-calculator.html
Gold is sold by the weight and it is not unusual to hear the price being quoted per ounce. This can be misleading for someone who has never bought or sold gold before because the ounces that gold merchants use are actually troy ounces and these are a different measurement than traditional ounces.
Of course, if you have measured the ring in grams because this is a more precise weight than fractions of an ounce, you will also have to convert your grams to a troy ounce. There are many conversion calculators on the Internet so you should find this easy to do.
If you do want to sell this ring, or any other gold, make sure that you do some homework before you do. There are many reputable buyers of gold; both on the High Street and online but you must remember that they will want to make a profit on the gold that they buy so do not expect to get its full value. Luckily this is a competitive market so you will have lots of buyers to choose from.