When Aret Oymakas started selling diamonds years ago, engagement ring shoppers came in looking for one thing for their brides-to-be: a real, mined diamond."It was just a diamond," said Oymakas, owner of Livia Diamonds in Toronto. "And you got what you were able to get … in terms of design and budget."These days, not so much. Lab-grown diamonds have become massively popular in recent years, giving the traditional, mined version a run for its money.Oymakas says natural diamonds made up 100 per cen...