RAPAPORT... The Plumb Club has signed up Evolution Diamond and Cynergy Trading Corp. as its newest members, the industry organization said this week.Evolution is a lab-grown diamond manufacturer specializing in bridal, fashion and men's jewelry, The Plumb Club said Monday. Cynergy is the North American arm of India-based diamond-jewelry manufacturer Creations Jewellery."Both companies will be great additions to our roster," said Michael Lerche, president of The Plumb Club. "The advantage that the club provides members has grown significantly over the past year, with many of our new programs and the introduction of [business-to-business virtual sales-meeting platform] TPC-365. I'm sure the addition of these two new members will be a great asset for both the companies and The Plumb Club."The additions bring The Plumb Club's membership to 45 businesses, representing more than 100 brands, the organization added.Image: Jewelry manufacturing. (Shutterstock)