Black diamond (also known as black diamond or carbonaceous diamond) is a natural polycrystalline diamond, which is found in alluvial deposits in Central Africa, China and Brazil. Its natural color is black or dark gray, and diamonds with more pores than other diamonds have become one of the most popular decorations in the upper class. Among all kinds of diamonds, black diamonds are especially precious because of their scarcity. Among the popular retro styles in recent years, represented by the tragic jewelry style of Victorian era, black diamonds have become the new favorite of fashion. As a widow, Queen Victoria of England always wears only black jewelry to show her eternal sadness. At that time, the black gem became the protagonist on the jewelry stage. Now, when many new materials are added to this kind of jewelry, such as black pearls and other precious stones, black jewelry has lost its sad mood.

In the past, black diamonds were generally used as collectibles, and some of them were used as treasures in jewelry stores. French jewelry brand Kexin once displayed a black diamond weighing 88 carats when it was published in 1996, which attracted the attention of many collectors. In September, 2008, the famous "Dream Star" brand was also launched in the jewelry exhibition held in Taiwan Province Province. The color of black diamond is black or dark gray, and it is a popular ornament that attracts the attention of the upper class. There is no specific quotation for black diamonds in the market, so it is difficult to estimate the price of 1 carat black diamonds. The price of black diamonds is definitely higher than that of ordinary diamonds.