What most naturally follows?

How to spell the color gray
Use " gray " for american english.
If you're in the united states, the most commonly accepted way to spell the term is with an-" gray. "
In the united states, " gray " appears roughly 20 times for every appearance of " grey.
" Use " grey " for british english. If you're in the united kingdom, canada, or australia, the term should be spelled with an-" grey.