Emerald Splinter

You transmute a piece of glass into a volatile green crystal and fling it at one creature within range. Make a ranged spell attack against the target. On a hit, the target takes 1d4 force damage. Hit or miss, the crystal then explodes into a viscous caustic substance. The target and each creature within 10 feet of it must succeed on a Dexterity saving throw or take 4d4 acid damage. If the target was hit it automatically fail this saving throw.

As part of casting the spell you can exchange the material component for an emerald gem worth at least 50 gp. When you cast the spell in this manner hitting the target will alter its nature, giving it vulnerabilty to acid damage until the end of your next turn. The gem is consumed by the spell. 

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, the acid damage increases by 2d4 for each slot level above 1st.