Dianond Tiara is a pink earth pony school filly. She's usually seen with a diamond tiara on her head, and Silver spoon tagging along beside her. She's in a class taught by Cheerilee, and her class mates include the main cmc, and several others.

Diamond Tiara is in almost all cases portrayed as a snobby brat, or a massive bully towards the cmc. She refers to them as "Blank flanks" or sometimes "Cutie mark cry babies". She's also rude and snobby towards other classmates, and sometimes, older ponies.

Diamond Tiara and Silver Spoon are shown in "Twilight time" To have a particular interest in princess' and celebrity ponies.

Her cutie mark is a blue tiara.