Crystalline-growth torus

Most of the ring is left smooth. A single cluster of crystal cones grows along one outer arc, so the texture is concentrated instead of spread evenly around the form.

u_k = u₀ + (rand₁ − ½)·span
v_k = rand₂·0.4 (outer equator)
L_k = L·(0.4 + 0.6·rand₃), s_k = s·(0.6 + 0.8·rand₄)

Every random number comes from a deterministic hash, rand(k) = fract(sin(k·127.1)·43758.5), so the same crystal count always grows the identical cluster: nothing jitters while you drag a slider.

Each crystal is a five-sided cone. Its base sits on the torus surface at (u_k, v_k) and its axis is that surface normal tilted by up to 18°, with the apex at P_k + L_k·d_k. Facets are flat-shaded, so neighbouring facets catch the light in clearly separate planes — that faceting, not a texture map, is what reads as crystal.