- Blue Diamond – $3.93 million per carat
Blue diamond is a type of diamond which exhibits all of the mineral ‘s inherent properties except with the stone’s additional element of blue colour. They are colored blue by trace amounts of boron which contaminate the structure of the crystalline lattice. Blue diamonds belong to a diamond subcategory called fancy color diamonds, the generic name for diamonds displaying intense colour. Blue diamonds range from Flawless to Included in grade as is the case with white diamonds.
2. Jadeite – $3 million per carat
Jadeite is the purest, rarest, and most vivid gemstone in the Jade family. Jadeite is a pyroxene mineral with composition NaAlSi2O6. It is monoclinic. It has a Mohs hardness of about 6.5 to 7.0 depending on the composition. The mineral is dense, with a specific gravity of about 3.4.
The “Hutton-Midivani Necklace”, which consists of 27 large, top quality jadeite beads, did just that. After twenty minutes of intense bidding from eight potential buyers, the piece sold for $27.44 million to Cartier, the original designer of the necklace.
- Pink Diamond – $1.19 million per carat
Pink diamonds are extremely rare. Only 0.0001% of the diamonds in existence are pink. It is a gemstone that would give beauty and harmony to the world. Just like white diamonds, pink diamonds can range from flawless to (heavily) included. The Pink Star is the only pink diamond in the world that is completely flawless.
In 2017, a stunning pink diamond weighing 59.60-carats was sold at a Sotheby’s auction in Hong Kong for a record-breaking $71.2 million. That’s $1.19 million per carat. Known as the “Pink Star” diamond, it’s the largest Fancy Vivid Pink diamond ever graded as Internally Flawless by the Gemological Institute of America.
4. Red Diamond – $1,000,000 per carat
Red Diamond is a diamond with the same mineral properties as colorless diamonds, displaying red color. They are commonly known as the world’s most expensive and rare color of diamonds, more so than pink diamonds or blue diamonds.
It is like pink diamonds, are highly debated as to the source of their color, but the gemological community most frequently attributes both colors to gliding atoms in the structure of the diamond as it undergoes tremendous pressure during its formation.
5. Emerald – $305,000 per carat
Emerald is a gemstone and a variety of the mineral beryl (Be3Al2(SiO3)6) colored green by trace amounts of chromium and sometimes vanadium. Beryl has a hardness of 7.5–8 on the Mohs scale. Most emeralds are highly included, so their toughness (resistance to breakage) is classified as generally poor.
At the Christie’s auction, it was purchased for $5.5 million, or $305,000 per carat. That made it the most expensive emerald per carat ever sold.