C. 1980 Vintage Black Opal Balloon and Flowers Pin in 14kt Yellow Gold

14KT: Karat (abbreviated kt or K) is a unit that indicates the purity of gold in the metal. 14kt is 58.33% gold. In the United States, 14K yellow gold is most favored and used in jewelry.

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.

OPAL: With an iridescent luster that can reveal a beautiful kaleidoscope of color, the opal has inspired many myths and legends. A white opal with swirls of soft pastel shades is popular for jewelry, but opals also come in black and blue. Opal is the gemstone for October birthdays.

OVAL: An elliptical shape that resembles an egg.

CABOCHON: A style of cutting gemstones to achieve a smooth, domed surface with an absence of facets.