How big are they normally ? I am looking at a parcel of 2mm stones and was tempted to buy it but I really do not know how big that is...

Some shanks are 2mm. I think micropave is 1mm on average. Regular pave maybe 1.5 - 2mm...I'm no expert though. It just depends on the look you are after.

2mm stones are "3 pointers" (as in .03 cts) and I think that's generally how melee diamonds are described, at least on PS?
From a quick search over PS, it looks like .5-1 pointers will give you you a very thin halo, and 1.5-2 pointers a slightly more substantial one, though still delicate. I didn't find any 3-pointer halos in my quick search.
Here's a ring with 3 pointers in the band:
http://www.briangavindiamonds.com/engage...te-gold-5483w18
It seems really pretty in the band, but I think it might be a bit too big for a halo, unless you're setting a HUGE stone or want a chunkier look.

From an online site, here's a conversion table for points to mm for round brilliants:
0.01ct (1 point) = 1.3mmm
0.02ct (2 points) = 1.7mmm
0.03ct (3 points) = 2.0mmm
0.06ct (6 points) = 2.5mmm
0.10ct (10 points) = 3.0mmm
0.25ct (25 points) = 4.0mmm
0.50ct (50 points) = 5.0mm
0.75ct (75 points) = 6.0mm
1.00ct (100 points) = 6.5mm

ohh sweet! that is so informative!

Cattrail, make sure you have some one that will use pre purchased melee. Many vendor will not use others stones for melee, unless it is something they cannot source themselves.

ahh thanks for the heads up JCent, they are pink diamonds and I was thinking of having them set with a 9mm OEC Amora in rose gold.

I emailed David to ask if he would work with them or not

THat would suck if I bought them and couldn't use them!

He may say yes But some will not and will want to source them themselves... more $$$$ that way. Hopefully he says yes for you.

So, I have 18 1.5mm diamonds in my setting. What would that translate to carat-wise?

A 1.5mm diamond should be about .015ct, so 18x.015=.27.

So about .27ct? There's a little wiggle room up or down.

huh. I thought most melee was 1 point. learn something new every day!