Diamonds are hard to get. Use these free methods to stack diamonds without spending Robux.
Claim daily login reward every day. Day 7 gives 500 diamonds. Don't skip.
Break coin jars in Tech World. Each jar gives 5-20 diamonds. Route: teleport between Tech World and Void World.
In Fantasy World, behind the crystal castle, there's a hidden diamond chest. Respawns every 4 hours. Gives 250 diamonds.
Fish in the event area. Rare fish can be traded for 50-200 diamonds. Use golden fishing rod for better rates.
Sell unwanted pets for diamonds. Common event pets sell for 100-500 diamonds. Check value list before trading.