Margins on diamond products are getting lower, but diamond "staples" still account for most of retailers' sales, an exclusive new JCK survey shows. The poll of JCK's retail panel, which drew 195 responses, also shows widespread misgivings about brands but high acceptance and support for Ideal cuts and grading reports. The main findings: Nearly half of respondents charge a 40% or greater margin for diamond staple products. Another 27.5% say their margins are 50% or better. Even so, nearly half say their margins are lower than five years ago. Some 34% said they were holding steady, and only 16% answered "higher." With diamond fashion items, the percentages were reversed. Exactly half (50%) of respondents said that margins were the same as five years ago, while 34% said they were lower, and 16% said they were higher—almost the same percentage that answere