While trainer Anthony Cummings is ensconced in Melbourne for the carnival, his foreman son Edward is happy to stay home, especially on days like Saturday when he led in a treble at Randwick.

Best Case got the ball rolling with victory over 1600m before Strike The Stars made a welcome return to the winners' list over 1400m.

The star of the show was Diamond Earth who claimed the last race on the program, the Group Three Nivison (1200m).

"What she lacks in size she makes up for in heart and speed," Cummings said.

"She will probably go to Melbourne. I'm not sure what Dad has in mind but I'm sure there's a race for her.

"It's the logical step."

When early leader Golden Sunshine compounded in the straight, Diamond Earth ($11) assumed control to beat Plucky Bell ($20) by three-quarters of a length with Hidden Kisses ($14) another length third.

Favourite She's Clean ($2.40) finished last of the 13 runners and there was speculation the mare was in season.