Magical gene / ground and strong white

Iridescent Jewel Beetle Coat

A coat that runs through the spectrum from one flank to the other, pitted with dark punctures in warm haloes - the shell of a jewel beetle.

What it can come out as

OutcomeCarrying
Iridescent Jewel Beetle CoatIjw/Ijw · Ijw/Ijm · Ijw/n
Iridescent Jewel, mutedIjm/Ijm
Wild typeIjm/n · n/n

How each one is actually drawn - region by region, and the layers it is built from - is on the coding tab.

Crossing two of them

Finding one

About 1 in 3,571 wild horses is born showing this. That is the whole of the supply: catch one, or make one with the carrot below. Breeds set their own pools and a breed built around this gene will carry it far more often than the wild population does.

Wild pairShows asHow often
Ijw/IjwIridescent Jewel Beetle Coat0.001% — 1 in 100,000
Ijw/IjmIridescent Jewel Beetle Coat0.004% — 1 in 25,000
Ijw/nIridescent Jewel Beetle Coat0.019% — 1 in 5,263
Ijm/IjmIridescent Jewel, muted0.004% — 1 in 25,000
n/nWild type99.972%

Its gene carrot

The file

common/src/main/resources/horsegenetics/genes/iridescent_jewel.json — a data-driven gene, not a Java class. It is listed in the index.json beside it and registered by Genes' class initialiser at startup.

Keyhorsegenetics.iridescent_jewel
Phasemagical — it adds signed colour in phase 3, after the pigment has resolved
Priority223 — where it sits in the one (priority, key) paint order
AllelesIjw · Ijm · n
Varies per horse8 values drawn once off the expressing allele copy, so a foal that inherits the copy inherits the look
Built fromAXIS, PARTS, RAMP, SPOTS, TOWARD

Why it is built this way

Imported from the magic-gene intake, 2026-09-08. The source gave the sheen as a five-stop hue ramp along Z. RAMP here takes a start hue and a span rather than a stop list, so this is one hue knob and a 210-degree span - two thirds of the wheel, which covers the same ground with one number a horse can inherit.

A RAMP varies colour along an axis and never coverage. That is why the sheen covers the whole barrel and fades nowhere; to fade it you would fade the mask, not the ramp.

What it paints

Each outcome, described the way the gene file describes it, and then the layers that draw it in the order they are painted. The prose is the part a reader checks a bake against; the list underneath is what the engine actually did.

Iridescent Jewel Beetle Coat

A RAMP along Z - centre of the horse to its right side - carries the hue a long way round the wheel, so the flank, the barrel and the belly are three different colours on one animal and the change is continuous. A ramp only varies colour, never coverage, which is why the sheen covers everything and fades nowhere.

  1. the whole barrel run through the spectrum — PARTS, painted with RAMP
  2. the hindquarter darkened, the way a shell is — AXIS inverted, painted with TOWARD
  3. a warm halo round each pit — SPOTS, painted with TOWARD
  4. and the dark pit inside it — SPOTS, painted with TOWARD

Iridescent Jewel, muted

The same shell with the spectrum run over a much narrower arc, so it reads as one colour shot with another rather than as a rainbow. Fully recessive.

Same ramp, span cut from 210 degrees to about 55. One knob is the difference between a rainbow and a shot silk.

  1. the whole barrel run through the spectrum — PARTS, painted with RAMP
  2. the hindquarter darkened, the way a shell is — AXIS inverted, painted with TOWARD
  3. a warm halo round each pit — SPOTS, painted with TOWARD
  4. and the dark pit inside it — SPOTS, painted with TOWARD

Wild type

No sheen.

Paints nothing.