In my opinion, there should be one with more charges. the current charges seems quite low-
My suggestions would be;
Normal: 150 Charges
Cost
25 Diamond Blocks
50 Iron Blocks
50 Gold Blocks
Rare: 350 Charges
Cost:
50 Diamond Blocks
50 Gold Blocks
25 Emerald Blocks
Legendary: 750 Charges
Cost:
10 Coloshite
10 Alexandrite
15 Sapphire
(that could also increase the usage for Sapphire, since currenlty its barely ever used at all)
Crafting in the shape of a Shovel, order that i put above