'Best' is a judgment and you are the judge.
Take your diamonds and their settings to a certified gemologist, who will help you document the diamonds as to their clarity, colour, cut and carat weight, and who will also help you determine composition of the setting metal.
If the setting is signed by a named designer, the design alone may have value.
Though you do not need a license to specifically sell diamonds you do need a jewelers license to sell diamonds. If you want to sell diamonds it will require you to fill out applications for a jewelers license once you have completed that you are eligible to sell diamonds.
Best practices dictate that you take your jewelery to a certified gemologist who will help you document your diamond(s) according to cut, colour, carat weight and clarity. This will help you determine a market value. Once you have an idea as to the value of the diamond(s), you can decide to sell them separately, as a group, or mounted in a setting. Remember that the setting has its own, separate value.
There are many places to sell diamonds. Online there are sites that can be used such as WP Diamonds, Sell My Diamonds and Cash for Diamonds. Local antique dealers may offer cash for diamonds, if this is preferred, rather than sending them in the post.
IT will be worth less. but it depends who you are selling it too if your selling it to some one who will wear sell with diamonds if not take diamonds out and sell those separately
Beverbrook jewelers only sell cut diamonds at this time. In fact, they don't even sell separate stones anymore, only diamonds that have been set in jewelry.
Terrorists, war lords, and criminals all sell conflict diamonds.
Best is a judgment and you are the judge. The best diamond store for you may be one that is willing to educate you about diamonds and help you acquire or sell a gemstone that you want.
Mappins sells jewelry. They specialize in diamonds and engagement rings. They consider themselves to be fine jewelers. The company has been in business since 1935.
You can sell diamonds to any local pawn shop ( won't be a great price), or try a jewelry store.
Yes, you can sell your expensive diamond jewelry online. Cash for Diamonds, WP Diamonds, Wabash Diamond Buyers, Cash for Diamonds and Circa Jewels are online websites where you could sell your expensive diamond jewelry.
ToysRus
Dallas Gold and Silver on Camp Bowie, They also buy diamonds.