Pierce Brosnan, as architect Sam Carmichael, wears Persol 2720 sunglasses (turtoise frame, green lenses) in the 2008 movie Mamma Mia! These are the exact same Persol sunglasses as the ones worn by Daniel Craig (as James Bond) in Casino Royale.
There is only one version that is the correct one (as seen in the movie), and that is the Persol 2720 with color code 24/31 (turtoise frame and green lenses), but some people prefer the black version with grey lenses (color code 95/48). Both are still available at several online stores, some of which are listed below.
The glasses are available with and without Polarized glasses, this can make quite a difference in price.
There are two sizes of this pair available, so be sure to order the correct size, or visit your local glasses centre and ask them to adjust the width of the temples to get that perfect fit.
Reference: Persol PO2720-S - Color: turtoise (code 24/31)