18 karat gold - 18k or 750 (the European designation meaning 75% gold)
14 karat gold - 14k or 585
9 karat gold - 9k or 375
The most common form of gold used, yellow gold is created with an alloy of silver, copper and zinc mixed withgold. The resulting yellow colour reflects the natural colour of the gold. Yellow and white gold are similar in strength and durability. It is the karat weight and design, not the colour that determines the price.
White gold is created by an alloy of nickel and other metals (copper and zinc) mixed with gold. Nickel is the largest component of this alloy, giving the gold a white colour.
White gold can also be made with an alloy that contains a higher concentration of silver, making it a good choice for people with sensitivity to nickel.
White gold is highly reflective and does not tarnish so it is common to add a layer of plating called "rhodium" plating that will protect the reflective quality of the white metal. This does not detract from the value of the metal.
While yellow and white gold are similar in strength and durability, it is karat weight and design, not the colour that affects the price.
Sterling silver is an alloy of silver and other metals, usually copper containing 925 parts per thousand with remaining 75 parts being other metals. Fine silver 99.9% is generally too soft for everyday wear. Copper is alloyed to give it strength while preserving ductility of the metal and its beauty.
Vermeil is a combination of Sterling Silver with a layer of gold on top. To be considered vermeil, the gold must be at least 9 carat and be at least 1.5 micrometres thick.