Graciliclava costata is a species of sea snail, a marine gastropod mollusk in the family Horaiclavidae.

Its colour is dull white, the summit buff-yellow, base anterior to the insertion of the lip pale orange-yellow.

Its sculpture consists of eight thick and prominent ribs to a whorl These descend the shell vertically and continuously; on the base they are slightly flexed, and each terminates anteriorly in a bead.

On the smooth glossy protoconch is a pronounced median keel, which ends abruptly at the topmost rib.

Behind the lip is a prominent varix which, rising above the suture, fills an intervariceal space on the preceding whorl.