Mark Caleo's conviction appeal related to his having faced a joint trial with Alani Afu, who was ultimately found to have stabbed his Asian wife, Rita Caleo.

An associate testified that Afu asked him to sell some jewellery, saying he had "killed a Chinese chick for it" and the "job" was given to him "by the husband of the Chinese lady".

Caleo was jailed for at least nine years in 2018 after a Supreme Court jury found him guilty of soliciting the murder of his 39-year-old wife, who was stabbed 23 times at the family home in Double Bay in August 1990.

The then 55-year-old was acquitted of soliciting the murder of his brother-in-law, Dr Michael Chye, 39, who was shot in the head as he drove into his Woollahra home in October 1989.

Afu, 51, was jailed was at least 15 years for murdering Ms Caleo in her bedroom late at night in a crime made to look like a robbery-gone-wrong.

Caleo had unsuccessfully applied to be tried separately from Afu.

The NSW Court of Criminal Appeal on Friday dismissed Caleo's conviction challenge, rejecting a claim that the failure to order a separate trial resulted in a substantial miscarriage of justice.

Chief Justice Tom Bathurst, sitting with Justices Robert Beech-Jones and Natalie Adams, said the trial judge had directed the jury that the evidence about the "husband of the Chinese lady" was only admissible against Afu.

The jurors were not to take it into account in the case against Caleo.

The Chief Justice noted that appellate courts generally assumed "juries understand and follow the directions given by the trial judge".

Almost immediately after the evidence, the trial judge gave the jury "a clear and firm direction", while he repeated it during his summing up of the case.

The appeal court said the evidence "was not so significant" that, notwithstanding the direction, there was a real risk the jury would take it into account, depriving Caleo of a real chance of acquittal.

The sentencing judge described Caleo as being an embittered husband to an older woman with whom he had fallen out.

He had become besotted with a much younger woman.

"Dissolution of the marriage would have necessitated a property settlement in which at least half of their joint property would be lost to his wife.

"Mr Caleo saw the way forward in a cold-blooded plan to get rid of his wife by having her murdered."

Afu acted as a "hired killer, carrying out his master's bidding with little hesitation".

Australian Associated Press