I think that there should be a trade at /warp grass that lets you trade Diamonds for grass. This will allow easy conversion from Diamonds to grass when needed.
Outcomes are needed for Diamonds to be used up, to control Inflation. Diamonds could be traded in for other things as well. Support.
Support, it could provide a base price for the trade of grass and diamonds so the prices don't keep going up :eh
Support, people sell diamonds for sometimes like 19 grass each and of course you will buy it from them. On the other hand you see people like BlockShop selling diamonds for 25 grass, he has lots of diamonds in stock and lots of other tradeshop's don't have lots of diamonds in stock so it will be easier to go to blockshop. Lots of people don't want to spend time looking for a tradeshop forever so I think this can reduce the ammount of time that you spend in chat asking if anyone sells diamonds, and also, this reduces some of the spam in the global chat due to some people spam to ask for diamonds. Support!