Certified memory?

A friend of mine ordered Micron memory via Crucial site instead of buying in a store,
because, as he explained, that’s the only possible way to get certified memory. As he thinks,
the memory with guaranteed quality, speed.
Never heard of it, but I don't have much reason do not believe in what my friend says about computers.
Anybody heard about certified memory?

You're absolutely right, Arrow. After you’ve posted your reply, later I got similar explanations on that.
Thank you very much.

What I saw today, that friend of mine is assembling an UNIX server, probably for his work purpose, that’s why he’s very concerned about memory quality.
And I learned from others about shady dealers who relabel RAM. Just like with processors, many RAM modules can be run higher than is marked so stores also remark RAM. A lot of PC-66 will run on a 100Mhz bus so it could get relabeled as PC-100 but it will fail the actual PC100 tests. And the same goes for some PC100 that will run on a system with a 133 memory bus and will get relabeled as PC133 but doesn't really fit.
And I was provided with the comparisons have been done on one computer with both generic and Crucial RAM using SiSoft Sandra:

Generic P-133 SDRAM from CanadaComputers.com:
Memory Module 2
128MB 16x(8MBx8) SDRAM PC133U-333-542
(CL3 upto 133MHz) (CL2 upto 100MHz)

P-133 SDRAM from Crucial.com:
Memory Module 3
Micron 8LSDT1664AG-13EB1 1A046EB5
128MB 8x(16MBx8) SDRAM PC133U-222-542
(CL3 upto 143MHz) (CL2 upto 133MHz)

Crucial P133 runs for SURE @ 133mhz and much faster when you go into your BIOS and set the RAM to run at CAS3 which is 143mhz. But so called P133 ram you find at most computer stores are the generic sh.. which doesn't reach the 133mhz speed all the time.