Keystones rhymes with:
keystone's, keystone's, blackstone's, bridgestone's, cherrystones, cobblestones, cornerstones, firestone's, flagstones, folkstone's, gallstones, gemstones, gladstones, gravestones, hailstones, headstones, keystone's, limestones, livingstone's, madstones, milestones, moonstones, redstone's, rhinestones, tombstones, waterstone's, yellowstone's
Keystones sounds like:
kading, kaeding, kastens, kazakhstan's, keating, keating's, kesting, keteyian's, keystone's, khatami's, kidding, kidneys, kiting, kittens, koetting