Artist's description from DA:Snide and crass through and through, Diamond Tiara was essentially unmoving in her spoiled daddy's girl ways. Although she never softened up and found it hard to play nice with others she stopped picking on the CMC and other classmates when Silver Spoon left town and her father's large estate was reduced to rubble. Her father and she moved into a small apartment and it became obvious how ill-adjusted Diamond T was. Filthy Rich had to travel often in order maintain consistent profits and She was often left home alone, without knowing how to cook or clean or anything like that.
The CMC took pity on her when they saw her struggle. Granny and Rich discussed the matter and it was decided that when Rich was out of town Diamond would stay with the Apple's and assist them in daily work.
Diamond was reluctant but had no trouble at all picking up the skills. She's not dumb or a clutz after all. SHe just complains a lot.
Granny took her under her wing and taught Diamond Tiara everything there was to know about Zap Apples. Absolutely everything. Even things Apple Bloom didn't know. Diamond became very good at making Zap Apple jam and pies and especially at keeping the timberwolves away from the ripening fruits before harvest. Just a few loud shouts from her and the wooden canines would be backing off with their twiggy tails between their lumber legs. Very few were dumb/brave enough to confront Diamond.
Diamond is a few months younger than any of the CMC, one of the youngest school foals from the show.