The 315 of the 2315 is for a masterwork longsword, already paid for by the free +2 enhancement. The resulting 2000 would add onto the 32000.
So
32,000 + 2,000 = 34,000 - 8,000 = 26,000/2 = 13,000 +1,000 = 14,000
Ciao
Dave
But: adamantine must be added to a new weapon, not to one already made...