Black is faceted obsidian 2.5mm. Red is optimized spinel 2.5mm, 6 9k gold beads, and 24k gold buckle.
Black is the preferred grade of obsidian, a halo is faintly visible in the sun, and the faceted craftsmanship imparts light and shine.
Red is a red spinel with optimized facets. The color is as deep as cow's blood, with good transparency and gloss. The bead diameter is small and faceted. Different colors of spinels correspond to different chakras.
Because customization will affect secondary sales, customized models are non-refundable and non-exchangeable.