>>107891200I think there's a difference in effort spent.
For one, the diamonds are designs that were explicitly inspired by other artists and their works. For example, Sugar has said White was inspired by Nell Brinkley and Blue, Leiji Matsumoto.
I would assume most common gems don't get the same treatment and most are just quick doodles. This was probably the same with the fusions. Opal and Obsidian have clear eastern culture influences. Sugilite and Malachite are supposed to be freakish monsters and their designs reflect that, but I feel with later fusion designs the crew kind of forgot that they weren't supposed to all be ugly.
Same with the normal gems, early on we would see murals or Pearl's holograms depicting other gems and they would be very feminine and fanciful. Once we get to homeworld, most gems are utterly basic in their design and even gender neutral, with nothing interesting about them.
I think either the crew forgot the early appearances of gems or there was an in-universe explanation that wasn't communicated very well to the audience.
