Dwayne Dunn has won four Blue Diamonds, but the jockey is still waiting to see which horse he'll ride in pursuit of another.

That picture will become clearer after Saturday's Preludes at Caulfield when he rides Star Turn for Hawkes Racing and Zamzam for David Hayes and Tom Dabernig.

"I've usually got them worked out before now," Dunn said.

Dunn's four Blue Diamond wins in a row from 2005 to 2008 included three on Hayes-trained juveniles.

He was impressed with what he saw from Zamzam at Moonee Valley on January 29 when he rode another horse in the same race.

"She was very impressive to do so much wrong and still get the job done. Hopefully she takes good improvement out of that," he said.

"She's probably doing everything on natural ability. Her experience may let her down but she's got good ability."

Zamzam is the on the third line of betting for the fillies Prelude (1100m) at $8 with Gimcrack Stakes winner Calliope the $2.90 favourite.

Dunn, who rides the bulk of horses for Hawkes Racing in Melbourne, has ridden Star Turn in a jump-out at Flemington and said the colt impressed him.

"I just want to see it on game day," he said.

Star Turn was third on debut at Randwick in October before winning later in the month by three lengths at the same track.

He is a $6.50 chance for the colts and geldings Prelude.

Dunn said the focal point out of a recent jump-out was to try to get the colt to begin well as a slow getaway contributed to his defeat on debut.

"He needs to start well and put himself in the race," he said.

"He seems a very relaxed customer and 1200 (metres of a Blue Diamond) shouldn't be a hindrance."