C. 1930 Vintage 4mm Blue Glass Pin with Seed Pearl in 10kt Yellow Gold

10KT: Karat (abbreviated kt or K) is a unit that indicates the purity of gold in the metal. 10kt is 41.67% gold.

YELLOW GOLD: Gold is a precious metal with a natural yellow color. It is quite soft and often alloyed with other metals to increase its strength. The purity of the metal is indicated by a unit called a "karat," with 24kt having the highest percentage of natural gold.

REVOLVER: A safety that conceals the point of a pin and keeps it in place with a revolving lever mechanism.

GLASS: A delicate, translucent to transparent noncrystalline material made by fusing sand with other materials , such as soda and lime, and then cooling it quickly. Glass is used in anything from windows to drinkware. In jewelry, glass is used for ornamentation, to make doublets, and to simulate gemstones.

CULTURED PEARLS: Likened to the moon, pearls have been valued for their luminous glow and natural beauty for thousands of years. Today, high-quality cultured freshwater pearls make pearl jewelry affordable to all. Pearl is the traditional birthstone for the month of June.

NEAR-ROUND: A pearl that visually appears almost round.