I have the same problem, even with dry gloves. But here are some things I do.
Start with warm hands. Letting your hands get cold before you put them into the gloves cuts the time down in the water before they go numb. I wear a warm ski-type glove out of the water before suiting up and keep them on until the last second before I put on the diving gloves and get right into the water.
Pre-warm the gloves. I keep a tub of HOT water, and pre-soak my hands in the hot water right before getting in.
Good circulation. With dry gloves, I make sure there is good air flow to the hands. With wet gloves, I'd make sure the gloves are a good fit so the water isn't being exchanges, but not too tight that the blood flow is cut off.
Limit your dive time. With Reynaud's, for me it's like a switch goes off at about 47 mins in water temps below 40 degrees, so I plan my dive times to be shorter in the winter.
And most important, keep the core warm. With Reynaud's, when the core gets cold, the flow of warm blood to the hands and feet shuts down. Start with a warm body before the dive and have good core insulation.
I do all this (dry diving) and still have dives in the winter where my entire body is nice and toasty, but my hands hurt. It's what I live with to dive in the cold. But doing the things listed above have helped me a lot.