Some time is mean Plum Gold.
"As with many things, the percentage of gold content can be a more difficult question than it seems like it deserves. Jewelers have had pretty good scales for a long time and alloying accurately is not difficult. The problem comes when the finished item has more than one metallic component. Solder, for example, is traditionally a little lower in gold content so a piece that is assembled using solders will, in the aggregate, have a slightly lower karatage. This logic is why the US has allowed 13.50001 karat to be marked 14k. The Europeans have not taken the same approach. In Europe, 18k means a minimum of 18/24 gold and there are relatively severe penalties to the manufacturer for screwing it up. Not surprisingly, metallurgists have figured out that that extra 0.49/24 bonus is easy to arrange and can add up to a fair amount of money so American manufacturers developed a reputation for selling less than they were promising. The reputable manufactures have responded by selling ‘plumb’ golds, which means that they are using the absolute definitions and usually a little more just to stay out of trouble. Most manufacturers are now doing this and, actually, plumb solders are now readily available as well."In this case it doesn't look like Gold,but who know?
