As part of consumer protection, you should be aware that you should only buy diamonds and jewelry from members of the "Jewelers Board of Trade"
First of all, you need to be legally in the trade to be a member.
Most importantly, by doing business with a JBT member, you have extra protection knowing that you are dealing with the highest reputable in the trade.

What do you think about those in the trade who are not JBT members but have a spotless reputation?

Credit cards are good to protect your transaction, not the quality of work you would get from a JBT member.
Also, price is a factor.
Only JBT members can visit directly with the cutters (like I do) to get the best prices possible.
Having a spotless reputation is good, but you might not be getting the price and quality you deserve.
Consumers are very educated about the diamonds, but not about whom they're getting it from.
Just an extra confidence variable to look at, not cutting down non-JBT members.

"Only JBT members can visit directly with the cutters (like I do) to get the best prices possible"

Do you mean buying directly from the cutters? I have impression that today everyone can buy directly from the cutters. Moreover, when I published this site I was aproached by a few cutters with the offers to sell their diamonds through this site.

This fact is quite interesting - cutters are looking for more ways to sell their goods and some of them are selling directly to public. My point is that one should not be a JBT member to become a diamond broker.

Your point is well taken.
However, not everyone can buy from the cutters.
When people on Pricescope, for example, search for diamonds,they typically get 2 or more vendors selling the same diamond.
So using this example, who's the actual cutter?
Some cutters offer their services directly to the public. And most don't because they rather have vendors do the selling for them.
I deal with this everyday, so I know who sells to the public and who doesn't.
As for being a JBT member, most cutters prefer you to be part of the JBT because they feel a sense of respect for the trade and not some dot com company looking to make easy money.
I also agree with you that you don't have to be a JBT member to sell diamonds- anybody can do that. But, I was just trying to point out that consumers should know if people are truly in the trade or not.
If you disagree with me, please give me an example of any diamond on P-scope and tell me who you think is the cutter and I'll tell you exactly who the cutter is.
Thanks.

Established in 1884, The Jewelers Board of Trade (JBT) is a not for profit jewelry trade association whose primary function is to compile and disseminate accurate and reliable credit information among its members as to the financial standing, credit history and background of dealers of jewelry and related products. We promote the welfare of the jewelry industry in part through furnishing to our members highly specialized credit reports. We are sponsored and maintained by the manufacturers, importers and wholesalers of jewelry and allied lines.

In addition to compiling credit reports on close to 70,000 jewelry businesses in the United States, Canada and the Caribbean, the JBT assists its members in collecting past due balances from delinquent accounts and provides telemarketing and mailing list information on various segments within the jewelry industry.

So basically, if a company has sufficient financial back-up in order not to require such credit from vendors and suppliers, and gets EXTRMELY good prices because it pays all of it´s diamonds IN FULL prior to the delivery, then why should being, or not being graded by the JBT, or listed, affect their products, policies, or company in general?

The JBT was created for the jewelry industry, not the consumers. It rates your business so that other businesses decide if they should "sell" to you or give you "credit" or not.