This is made from the following method:

Rough Emerald + Coral Piece + heating = Green Coral
Green Coral + Titanium Ingot + heating(skilled) = Jade Coral Bar.

Ratios are, to my knowledge(June-25-2017), unknown at this time. The green coral one is known, but I don't know it off the top of my head.

800 of these bars are needed for the new battleship.

It's easy to obtain this, Just buy prairie Green Coral, Golden Sun Coral, Breezy White Coral, Twilight Red Coral, OR Daybreak Blue Coral from central market, buy Melted Titanium shard, and use heating on them. This may not the most profitable way. but it's the fastest way.