When buying jewelry online there are certain things you can look for that will help your confidence in the purchase.  First, always look on the inside of the shank (the part that goes around your finger) to see what material the ring is made of or if it's plated.  Here are some common markings; 8k - 8 carat gold, 9k - 9 carat gold, 10k - 10 carat gold, 14k or 585 - 14k gold, 18k or 750- 18 carat gold, 925 - sterling silver (will tarnish) 950 - platinum.  10k s the least amount of gold allowed in jewelry for sale in the US, 8k & 9k are usually from Mexico and Europe. The carat of gold is measured like this (24K is pure, so if it's 14k gold it's 14 parts gold and 10 parts alloy, the more alloy the stronger, but the less value the piece has)  If it has a GP after the caratage, it means that it's gold PLATED, you don't usually want that.  If its missing a stamp, be weary or ask the seller.   Also make sure to check the prongs (part that holds the stone in) make sure that they cover the part of the stone they are touching so you don't lose it in the future.  Also be sure to look at how the stone is set, prong set stones can be sized, tension set stones (where stone is held on edges and appears to "float") can be sized minimally, but check with seller on return policy if not able to size.  Of course there are many other things to look for, but these above are the main things to keep an eye out for to ensure a quality product.  Any other questions, just email me.  I was in jewelry for years and spent the last 5 yrs of my career in management so my knowledge in this area is quite proficient.