What is a glass optical cable?

Someone suggests from recent posts that glass optical cables are superior than others. What are they?

Where can I get a decent one for below 100?
I`m not sure what is the exact description is but look up Glass on the audiogon search. but captstripe ?? makes a good one. I bought one from him and it got here really fast and I am very pleased with it. It cost about $40 including shipping etc. It comes in 5 ft. length which is very accomodating.
Optical (Toslink) cables can come in plastic or glass. Sometimes you will see Quartz (glass) written on the box. I believe all of the Toslink cables at Radio Shack are plastic. Wireworld offers a very nice glass cable for about $135.00. I used this in my system for quite some time before I tripped over it and broke it.

I contacted The Cable Company for another one and I got a replacement (www.fatwyre.com) and they also loaned me an Audioquest Optilink which sell for close to $500.00. the difference is minimal but noticable. I now own them both.

Once you have your glass cable in place it is not wise to move it around too much as slight cracks in it will degrade the music. Also, if you can get a really bright light on black print you can see the outline of the words by holding one end of it against the typeface and looking through the other end.
I bought the 30 or 40 dollar glass cable on ebay (do a search for glass toslink there, it's the one from captnstarstripe), and sold the Wireworld Supernova cable I was using on a megachanger.

The ebay cable sounded a little better, or at least just as good, for 30% the cost of the Supernova.

Glass optical used to be a reference to ATT glass fiber cable which was a different, much higher quality data transmission line than toslink (ATT glass is the standard for telecommunications equipment.)
Many companies offered ATT digital on audio equipment and still do, which is what the term "glass optical" USED to refer to in digital audio interfaces.

It lost popularity due to the cost of the equipment to properly put a connector on the end, which is also labor intensive).
I also use Captnstarstripe's glass cables for every Toslink application in my system. They sound better than any non glass Toslink I've ever owned, although the priciest one I've ever owned only cost about $150. Captnstarstripe's were about $35 with shipping, and he gets them out to you FAST. I think they showed up within 48 hours of when I placed my order.