How can I earn more purple diamonds?

Besides removing rocks and dead trees from open plots, the next best way to earn diamonds is to find 6 players to exchange regular bushes on a daily basis, which can potentially earn up to 98 diamonds per week. Diamonds (purple gems) are the rarest currency in the game, so save and use them wisely. Some decoration can only be purchased with diamonds. You can also use them to speed up construction, to buy energy, to gift special bushes, to open land when you lack compasses, or to buy the extended energy bar.