These fun, fashionable pieces prove that diamond jewelry doesn’t have to be a luxury—or reserved for special occasions. Meet your new everyday dazzlers.   SAFETY PINS & LOCKS THE KEY TO YOUR HEART (Top) Diamond pavé heart lock and key necklace in oxidized sterling silver and 14k yellow gold; $388; Zoë Chicco, Los Angeles; 213-489-1226; zoechicco.com   A LOCK TO LOVE (Inset) Barleycorn platinum chain with a platinum lock and 0.75 ct. t.w. reverse-set baguettes; $5,226; Marla Aaron, NYC; 646-263-7642; marlaaaron.com    PIN UP, GIRL Aquamarine Pyramid safety pin earring with diamonds in 14k rose gold; $2,300; Jacquie Aiche, Beverly Hills, Calif.; 310-550-7529, ext. 101; jacquieaiche.com   SAFETY DANCE Safety pin bracelet in 14k gold and black rhodium with 0.13 ct. t.w. diamonds;