Rafael Usufally was more than eager to propose to Alexandria Kishore, his girlfriend of 11 years — but he wasn’t about to get down on one knee until he’d managed to create “the perfect moment.” First, the loved-up Long Islander would need a ring — and money was no object. What mattered most to the electrical engineer, 30, was wowing his now-fiancée, who works as an administrator at a neurologist’s office. So Usufally spent weeks poring over diamonds, finally deciding on a $11,000 radiant and