Adding a halo to any engagement ring is going to give you increased size. Adding a halo to a 3 stone engagement ring makes for even more size. 
What I love about combing three stone rings with a halo is that you get the sparkle of pave set diamonds, but you also get to appreciate the extra diamond shapes incorporated into the ring. Below are some of my favorite 3 stone halo engagement rings.
Emerald and Trapezoid Diamond Three Stone Engagement Ring
HE319 is a 3 stone ring featuring a center emerald cut stone with accenting step cut trapezoid diamonds. I love the combination in this ring because you have the strong linear faceting pattern through the center of the ring and then more sporadic sparkle coming from the periphery with the pave set diamonds. Anyone who loves an emerald cut diamond will love this design because it really highlights the features of the cut without losing the brilliance that we expect from a pave halo engagement ring.
Round Halo Three Stone Ring
A 3 stone round halo engagement ring is for the customer looking for maximum sparkle. Style HE3514 can be manufactured with any size center stone, which means this is also a great setting for someone who is looking to upgrade or reset their diamond. This design is also available in our rose gold morganite or sapphire engagement ring sections meaning there are a lot of possible variations for this 3 stone halo combination. Round brilliant cut diamonds measure very competitively in order to give the wearer maximum of finger coverage.
Floral Three Stone Halo Engagement Ring
Style HE296 is a rather unique 3 stone halo engagement ring. This ring features a partial u-pave style halo around the center stone and then two accenting side round brilliant diamonds. The design currently features a center oval diamond, although this concept can be customized to suit a variety of center stone diamond and moissanite shapes. The non-halo portion in the ring (the two side diamonds) gives a more cluster-like feel. This is reminiscent of Art Deco diamond rings, which feature a variety of setting styles. If you are interested in a 3 stone engagement ring that is unlike one owned by anyone else, this is a great design to consider.
*Update: This post was originally published on October 15, 2015 and was updated with new information on January 8, 2019.