Having done my research I have found a diamond that I would like to buy
for an engagement ring.

The diamond is 1ct and is GIA certifiied.

My question is: Can I trust it?

I have done my homework and "know" what I should or should be after -
in the basic sense on the term.

Having looked on other "high street" jewellers sites they say "We pass
on 95% of ceritified diamonds because they don't pass our test"

What is peoples opinion?

Thanks.

R