This is a CLOSED species called the Gem Scales. These are ponies that are based off of gems. They can be Unicorns, Earth Ponies, or Pegasi. They have a certain shape of gem on their chest and head. Their tails have Jewlry, or colorful silky rope on it. Their snake headed tails are the same shape as their jewel.
Example:
How to tell the Rareness:
Commons:
Common ones have only a jewel on their chest. Not the head. They are always Earth Ponies.
Uncommon:
Uncommon ones have only a jewel on their head and not their chest. They are always Earth Ponies.
Rare:
Rare ones have a small jewel on their chest and head. But are always unicorns.
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