Tourmaline is known as the gem of love and commitment. Buy her a pair of pink tourmaline earrings to seal the deal! White topaz is a popular substitute for the birthstone of April, which is diamond. A pair of white topaz earrings is an affordable alternative to expensive diamond studs. White topaz is a popular substitute for the birthstone of April, which is diamond. A pair of white topaz earrings is an affordable alternative to expensive diamond studs.