You can get 2 1/2" diameter diamond bits on Amazon.

drill a hole in the very center, stick a toothpick in it, tie a string around it and attach the other end to a glass knife, score the glass in a circle. I don't know if this will knock out easily, but you can always get a very small diamond drill bit and cut small holes all the way around the circle, then try to pop it out. Then you can sand the edge smooth. Sounds like a lot of work though.

>>920642
This is a great idea, thank you. And it took forever to find that 2-1/2 inch drill bit on amazon, but I did find it. I think I'll take the expensive and easy route instead of the cheap-but-hard route and buy the bit, lol

>>920702
Different poster but drilling lots of holes is called stich drilling.
I would probably do this rather then a 2 inch drill bit. Wont break or take years.

>>920713
I like when /diy/ is funny
>>920710
This would be my choice so far

find a 2-1/2 inch piece of steel and heat it up in a fire pit
stick it straight up in the dirt and push the bottle down onto it SLOWLY
it might take two or three goes but a diamond drill bit for one bottle is a huge waste of money and time.

I seriously can't believe nobody's brought fire into this equation

>>920713
Kek

>>920837
fire dangerous

A piece of copper tube and some polishing compound is all you need. Use the copper as a drill bit, keep the surface slick with the compound. The polishing granules will imbed into the copper and make it into a poorfag abrasive drill bit. Will take forever, but for just one hole, is probably your most economical option.

http://uk.tools4pro.com/diamond-bits-wet-cutting/288-kit-easy-gres-plus.html?gclid=CjwKEAiAtf6zBRDS0oCLrL37gFUSJACr2JYbpD_b6pC5TZPuPpCpc_iiDflKsfr01hHLpfuoMk6p5xoCYHTw_wcB

Search glass core drill.

Some fluorhydric acid can do the trick... or result in a very hilarious misadventure.

>>920641
Very first answer was correctish. Get a diamond hole saw.
>>920713
This was best though.