Fancy rats are identified by pattern, not colour alone
A fancy rat's markings are his identity, so describe the pattern in the terms rat people and rescues use. Note whether he is hooded, capped, Berkshire with a white belly, variegated, or self-coloured, and then add the individual layer: where the hood breaks, a spot inside the stripe down the back, one white toe, a kink or mark on the tail. Two hooded rats in the same rescue look alike until that layer is written down. Add his size, sex, ear type — standard or Dumbo — and whether his coat is standard, rex or hairless, because those three details narrow a found rat to a handful of candidates immediately.
Photos from the angles a finder will see
Photograph him from above to capture the full back pattern, from the front for face and ear markings, from the side, and with his belly markings visible if he will tolerate it during handling. Take the set in daylight against a plain background, and include one photo in your hands for scale. A finder who discovers a rat in a shed will compare against these angles, not against a sleeping hammock snapshot, so keep at least one clear, alert, whole-body image for each side. Refresh the set as a young rat's markings sharpen and after any lasting change — a scar, a lost fingertip of tail, a patch shaved for treatment.
Behaviour notes that help a finder confirm it is him
Identification is not only visual for a fancy rat. Note how he behaves with strangers: whether he comes to a hand, freezes, or runs, whether he answers to his name or to a treat packet sound, and which foods will reliably draw him out. Tell finders to offer food and a box or carrier to climb into rather than grabbing, and to support his whole body if he is picked up. Mention cage mates by pattern if a group escaped together, and note anything a holder needs immediately — an older rat who must stay warm, or one who needs soft food. A finder who can say 'he came straight to the treat sound and has the spot inside his stripe' has identified him twice over.
Circulate the pattern where rats are handed in
Send the back-pattern photo and description to local rescues, vet practices and small-animal groups as soon as he is missing, leading with pattern type and ear type rather than his name. Keep the same description on your phone, with family, and printed on his carrier for trips to the vet or a sitter, so the identity that travels with him matches the one you circulate. If he is found some distance away, that consistent wording matters: a rescue worker matching intake notes at midnight should never have to wonder whether 'grey hooded rat' and 'blue variegated, Dumbo ears' are the same animal or two different losses.
One card that ends the guessing
Test your description honestly: from the written pattern alone, could rescue staff pick him out of three similar rats? If not, add the odd spot, the toe, the tail mark until he could. Carrying that identity on KinsLe's Pet Pass puts his pattern, photos and your contact details on one verified ID card, so a finder or rescue holding your fancy rat can confirm the match and contact you without a chain of messages.