18 carat yellow gold ring with 6 carat cyanite and round princess-cut diamonds

Yellow gold : Yellow 18K gold is an alloy contianing 75% of pure gold, whereas 14K gold contains only 58,5% of pure gold.
Princess cut : Created in the 1960's the princess cut is the second most popular after the round brilliants. The princess diamond is most of the time cut as a square, but can also be as a rectangle.
Carat : The carat (ct) is a unit of mass equal to 2 g. Carat is used for measuring the weight of gemstones.
Diamond : In mineralogy, diamond is an extremely rare, precious and hard (named after the ancient Greek "unbreakable") metastable allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice.