While rings are the most popular way to wear a gem, those worn on other parts of the body don t get anywhere near the abuse a ring stone will. If you really want it in a ring there are a couple of things that can help your stone. Also consider the setting. A tiffany setting that holds the gem well up above the finger with a few prongs is asking for trouble. If you are putting a delicate gem in a finger ring, chose a setting with lots of metal around the gem to protect it.
Gold is soft, but easily polished and it is fairly easy to replace when it wears away.
There are other factors besides the ones we have already covered. Some are brittle, meaning they chip easily. Others, like opal are heat sensitive. Many soft and porous gems, like pearls and turquoise, are effected by chemicals. So, I hope you are beginning to understand that, in gemology, hardness alone is not a measure of durability.