If looks are anything to go by, then Rubick has passed the test with flying colours.

Trainer Gerald Ryan was happy with the colt when he saw him on Sunday for the first time in a week and even happier after he watched him work at Caulfield a day later.

The second favourite behind Earthquake for Saturday's $1 million Blue Diamond Stakes, Rubick had to work harder to win the colts and geldings Prelude on February 8 than Earthquake did in the fillies division.

Both ran the same time with Earthquake sprinting clear at the back end of the race while Rubick had to push up early and was noticeably tired at the finish.

"He looks enormous and he worked well with an older horse this morning," Ryan said.

"But I was really pleased with how he looked. He felt the run in the Prelude. It was a hot day and he knew he'd been in a race.

"But in the week since he's put the weight back on and you can see his muscle definition.

"He looks great and he's right for the race."

Rubick ran the last 400 metres of his work-out in 22.41 seconds and his last 200 in 10.68.

The Blue Diamond (1200m) on Saturday can accommodate a field of 16 with the barrier draw to be held on Tuesday.

After he started from gate two in the Prelude, jockey Brenton Avdulla said a wide barrier might give him more options.

But Ryan, who is trying to win a third Blue Diamond to go with victories by Hurricane Sky in 1994 and Paint two years later, said he could not worry about the draw.

"There's nothing you can do so we will deal with what we get," he said.