Normal (left) vs Shiny (right). Credit reddit user skinnysnorlaz They won't appear as a different colour in the field, so you have to attempt to catch them first. They of course can also appear in ...
Yes, the Sigilyph can be shiny in Pokemon GO. The Pokemon GO Tour: Unova - Los Angeles and New Taipei City events debuted shiny Sigilyph via 10 KM Egg hatch, with shiny odds of 1-in-64.