The Blue Diamond Preview (Colts and Geldings) is a Melbourne Racing Club Listed Thoroughbred horse race, raced under set weights with penalties conditions for two years old colts and geldings, over a distance of 1000 metres run at Caulfield Racecourse in Melbourne, Australia in late January.^[1] Prize money for the race is A$200,000. The race lost its Group classification in 2006.

The race is considered a lead-up to the Group 2 Blue Diamond Prelude C&G the following month and both races are used as lead-up races to the Group 1 Blue Diamond Stakes in late February at Caulfield.^[1] The race is usually held on the Australia Day public holiday.
Along with this event the Blue Diamond Preview Fillies is held.
Thoroughbreds that have captured the Blue Diamond Preview – Blue Diamond Stakes double:
Midnight Fever (1987), Zeditave (1988), Knowledge (1997), Bel Esprit (2002), Reaan (2008) and Sepoy (2011)

Prior 1996 the race was known as Blue Diamond Prelude (C&G) and was run at Sandown Racecourse and was not to be confused with the Blue Diamond Prelude C&G run at Caulfield Racecourse a couple of weeks later at a distance of 1,100 metres.

• 1982–1987 - Listed race
• 1988–2005 - Group 3
• 2006 onwards - Listed race

• 1982–1983 – 1200 metres
• 1984 onwards - 1000 metres

• 1988–1996 - Sandown Racecourse
• 1997–2005 - Caulfield Racecourse
• 2006 - Sandown Racecourse
• 2007–2014 - Caulfield Racecourse
• 2015 - Sandown Racecourse
• 2016 onwards - Caulfield Racecourse

• List of Australian Group races
• Group races