Amethyst has one bug being the fact if you are to do this in the correct order this happens:

1.You first place the block of Amethyst on any surface and place the amethyst crystals on any side. 
2. Once that is done you place other Amethyst blocks on all facing sides and above.

3. Then you break the block from step one and all other blocks excluding Amethyst crystals.

NOTE: To fix this would help the game be less broken as this is a bug that has not yet been fixed. Please fix this MOJANG.