Olivier Martinez reportedly answered a series of questions to help create a "masterpiece" engagement ring for fiance Halle Berry.

The French actor finally confirmed reports over the weekend that he had popped the question to the Oscar winning actress.

Olivier told The Miami Herald that the ring was designed by Paris-based jeweller Robert Mazlo who has designed pieces for "kings and queens."

And a friend of Olivier's told Us Weekly that he went to great lengths to ensure that the Hollywood star had the perfect ring.

"[Olivier] said he wanted to produce the most beautiful ring ever made," the pal explained about the meeting just before Christmas last year.

"Money was no object and he only wanted the finest materials involved."

The jeweller apparently requested that Olivier take a 500-year-old mystical "alchemy test" to determine what would be the best design to place on Halle's finger and which would "symbolise the couple's story."

He had to answer seven questions including her favourite colours, shapes, signs and numbers.

Robert then "decoded" the answers to come up with something that would best suit Halle and Olivier was "absolutely delighted with the result" which was "well into the five figures" price range.

The ring is a four-carat emerald from a Colombian mine and a "balance between the blue and the yellow in the green in that stone is perfect," the jeweller told People magazine adding that the ring contained symbols and codes that had hidden meaning.

The source added to Us that the couple's wedding plans were "not yet finalised" but there was a "very good chance it would be in Paris."

"It will be the first time round for Olivier he would love it to be in his home city the city he knows and loves," the insider said.

Halle first met Olivier on the set of the movie Dark Tide in South Africa. They went public with their romance in late 2010.

Halle who has a three-year-old daughter Nahla with ex-boyfriend Gabriel Aubry has been married twice before. She divorced baseball star David Justice in 1997 after five years of marriage and her four year union to singer Eric Bent ended in 2005.

Olivier has romanced famous faces including Kylie Minogue and Mira Sorvino, but has never tied the knot.