Q. What do the abbreviations K, KP, CT and CTW mean?

A. K is for karat, which indicates the gold purity.  24K is pure gold, 18K is 18 parts out of 24 parts pure gold (75%), 14K is 14 parts out of 24 parts of pure gold (58%).

When K is followed by Y or W it means yellow gold or white gold. For example, 14KY stands for 14 Karat Yellow gold.

Sometimes you will see a “K” followed by a "P".  “P” stands for "Plumb" gold. Under the US purity laws, gold must be within 7 parts per thousand of the stated karat.  Some manufacturers add the "P" to their stamp to indicate that it is plumb gold and falls within the purity law of the US.

CT is the abbreviation for carat weight. Carat is a measure of gem weight.  For a 14KW ring containing a 5.51 carat sapphire, you might see two abbreviations inside the ring; 14KW followed by a 5.51 CT.