The use of 18k gold in jewelry making signifies a choice for durability and luxury. Gold, particularly in its 18k form (which is 75% gold), offers a rich, warm contrast to the cool tones of gemstones like larimar. The term "full" might refer to the construction of the piece, implying it's made entirely from 18k gold without any filling or plating. This construction method ensures that the jewelry retains its value and appearance over time.