[The ring] symbolizes the couple's story, according to the designer of the ring.
Rumors first started to circulate after Berry was spotted with the ring on earlier this year. The couple remained mum about it, with Martinez finally confirming the news over the weekend in an article on Miami.com.
Martinez commissioned jeweler Robert Mazlo to design the one-of a kind bauble.
There is a jeweler taking credit for doing the ring and it's a lie, Martinez said. They have nothing to do with this.
[Mazlo is] a real artist, Martinez said. His family has been designing jewelry for kings and queens for many centuries.
[The ring is] a one-of-a-kind piece and cannot be replaced, the jeweler told People Magazine exclusively.
Martinez said he wanted to produce the most beautiful ring ever made, money was no object and he only wanted the finest materials involved, a friend told Us Weekly Magazine.
The ring showcases a four-carat emerald that came from mines now closed down in Muzo, Colombia.
[The color is] perfect, the jeweler said. The balance between the blue and the yellow in the green in that stone is perfect.
Martinez also wanted to make the ring special and meaningful to Berry. The ring also sports two diamonds in a textured, yellow-gold setting forged according to ancient Phoenician tradition.
The ring is textured and contains codes and symbols which you cannot see...only the person wearing it can, the jeweler said. It's very uncommon. The symbols and codes represent [the couple's] story and only they can interpret it.
Berry and Martinez have been dating since 2010, when they met on the set of their upcoming movie Dark Tide.
This will be the third marriage for Berry, who was married to former baseball player David Justice from 1993 to 1997 and to singer Eric Benet from 2001 to 2005. Berry also has a four-year-old daughter, Nahla, with model Gabriel Aubrey. The two are locked in a contentious custody battle.
Martinez has never been married, but has been linked to actress Mira Sorvino, singer Kylie Minogue and English model and actress Rosie Huntington-Whiteley.
No wedding plans have been announced publicly.
Not yet finalized, the friend tells Us Weekly. But, there is a very good chance it would be in Paris. It will be first time round for Olivier . . . he would love it to be in his home city - the city he knows and loves.
Halle Berry has not commented on her engagement yet.