Yellow Gold Diamond Tie Pin

Gold : Because of the softness of pure gold, it is alloyed with silver, copper or palladium. The proportion of these other metals give yellow, white gold. Without precision, the gold used in jewelry is 18 K, corresponding to 75% 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.
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.