.60 Marquise Cut Amethyst Engagement Ring in 14k. 60 Marquise Cut Amethyst Engagement Ring in 14k. This sultry marquise cut amethyst engagement ring features a . 60 carat purple amethyst and accent diamonds in 14k yellow gold. The natural purple amethyst has a faint lilac hue with elongated facets. Set in four prongs, the primary amethyst is complimented by a halo of accent diamonds shaped perfectly in marquise form. The shoulders of the band feature a row of accent diamonds that reach halfway