Toth, 40, gave his "Legally Blonde" future bride a blinding 4-carat Ashoka-cut diamond set on a diamond-and-pavé-adorned platinum band, People reports.
The ring was custom-designed with Toth's input by jeweler William Goldberg of the William Goldberg Diamond Corp. Goldberg told US Weekly that Toth, who works for mega-agency CAA, was drawn to the uniqueness of the vintage-style Ashoka cut, distinguished by 62 displayed facets and rounded corners. (The exact ring given to Reese has not been released; StyleList has selected an image from William Goldberg that most closely matches the description.)
Just 10 percent of rough diamonds have the potential to be Ashokas, making it a sentimental choice for the bride who has everything.
"The ring has a lot of significance because Jim chose such a rare diamond," Stacy Kottle, a gem expert and owner-designer of the Los Angeles-based Nolan line of jewelry tells StyleList. "It's the rarity of the cut that makes the stone truly unique."
The piece's estimated value is about $150,000, according to private estate jeweler, who looked at images of the ring for StyleList.
Kottle notes that while the ring's micro-pavé details are extremely popular and a trend in recent years, she's noticed preferences shifting toward "larger side stones and simple, polished bands." For Witherspoon's ring, "I personally would have encouraged a setting that is more substantial to better complement the size of the center stone."
We suspect Witherspoon, who has said through a rep that she and Toth are "very happy," is completely smitten with her big rock.
While the couple hasn't announced a wedding date, StyleList looks forward to a 2011 marked by a streak of celebrity weddings, including those of expectant Natalie Portman to ballet dancer and model Benjamin Millepied, LeAnn Rimes to Eddie Cibrian and "Bachelorette" star Ali Fedotowsky to chosen one Roberto Martinez.
Meanwhile, read about the sentimental ring 2011 bride Kate Middleton received from Prince William, and check out the list of 2011 celebrity weddings to watch on AisleDash.