Diamonds in the mantle variety via a metasomatic method wherever a C-O-H-N-S fluid or soften dissolves minerals inside a rock and replaces them with new minerals. The marginally misshapen octahedral condition of this rough diamond crystal in matrix is usual of your mineral. Its lustrous faces also indicate this crystal https://arshadjewellers.com/product-category/gold-jewellery/gold-bracelets-set/