Mystery of 18K Gold in the Apple Watch

The Mystery of the Gold in Apple Watch

Dr. Drang wrote, "Apple’s gold is a metal matrix composite, not a standard alloy. Instead of mixing the gold with silver, copper, or other metals to make it harder, Apple is mixing it with low-density ceramic particles."

To put it another way, Apple is combining gold with durable materials that don't have much mass, but take up lots of space. That gives it wonderful qualities like lightness and scratch-resistance (normal gold is somewhat soft and prone to damage). And by mass, the final product is still 75 percent gold. But when it's poured into a mold to make an Apple Watch Edition's shell, the other, not-so-precious ingredients take up most of the room. Apple gets to use less gold per cubic centimeter and still call it 18-karat. It gets to stretch its gold out further than, say, Rolex would, to make a watch this size and shape.

Excerpt taken from http://www.slate.com/blogs/moneybox/2015/03/09/apple_watch_edition_the_company_found_a_trick_to_use_as_little_gold_as_possible.html