Originally Posted by oceanmist /img/forum/go_quote.gif It depends upon their formula. Some minerals are really heavy and don't take up as much space as others so they can fit 13 grams in a jar. I haven't seen any 18 gram ones, but those must be high in titanium dioxide because that's about the heaviest mineral used. Iron oxides are pretty heavy as well, so some darker colors will be heavier than others. Thanks for the explanation. So if a jar says 13g or 18g, it is a heavier powder your getting, not necessarily more product? That's good to know - my jars are packed full and smashed down by the sifter, so I'm happy I have a full jar and net wt doesn't really matter!