This has a width of 5.9cm and a height of 5cm. It's a nice silver, and is shiny, but not glossy. The points are quite sharp, so it you shouldn't wear this if you're gonna be running, jumping, etc.

It comes with a leather strap without a hook, so you have to attach one yourself or tie it up. I choose to tie it up, and it works fine.

Here's another one- same symbol, but much smaller. This one has a width of 2.2cm and a height of 2.8cm. Has a nice glossy shine, which is enough to reflect (distorted) images.

The symbol is not painted/printed, but is a depression, thus creating distorted reflections. Have worn this many times, but no signs of fading is showing and is still maintaining it's shine. Symbol repeats on both sides. This is a very good buy.
Cost:
First Geass necklace- RM 20
Second Geass necklace- RM 15.90
Prices stated are according to what I remember, and therefore, might not be accurate.
Both of these can be found @ Anime·tech in Mid Valley Megamall.