If you have thin ankles…
…beware of hefty heels. They dominate the shoe, make your feet look enormous and exaggerate the skinniness of your ankles.
More elegant heels will allow the wearer to show off her ankles to the best advantage without the shoes detracting from them and drawing too much attention to your feet.
So the heel on the left is a bad choice for thin ankles because the chunky heel is overpowering. The slender heel on the right is much more flattering for dainty ankles.