We often see people use these terms interchangeably, but they mean two different things.
Pure Gold:
Pure Gold refers to the karat of gold. Only 24k can be considered pure gold, all other karats of gold are alloys because they are mixed with other metals. Because of its purity, you will only ever find 24k gold in its natural yellow color.
Solid Gold:
Solid Gold refers to the structure of the piece. Solid gold jewelry is made entirely of gold and is not hollow or plated. Solid gold can be any karat or color of gold, but cannot be called Pure Solid Gold unless it's 24k.
