What is known as yellow gold in the Caribbean?

Sand

While most of the beaches in the Caribbean have white sand there are a few with yellow-gold sand. Which is why those are called "Caribbean Gold"

Let’s look at the standard, gold-color beaches, which can be found in Southern Europe. Their sand is formed of quartz, which contains traces of iron that give the yellow/gold color. Quartz without those impurities forms white sand. This is common in beaches in tropical regions such as Cape Santa Maria in the Bahamas or those beaches found on Caribbean Islands.