3-3.5 , Q.1 Blue : Natural Sliced Dyed Agate Coaster with Rubber Bumper Set of 4 (Q.1 Blue, 3-3.5"), By JIC Gem

Q: Are they gold on the edges?

Not for this set. We have gold on the edges set on other links. FYIhttps://www.amazon.com/JIC-golden-plated-coasters-natural/dp/B01M271DG5/ref=sr_1_1?ie=UTF8&qid=1491853886&sr=8-1&keywords=B01M271DG5https://www.amazon.com/JIC-Gem-Golden-Plated-Coasters/dp/B01M9DHQ2N/ref=sr_1_3?ie=UTF8&qid=1491853910&sr=8-3&keywords=jic+gem+agate+coaster

Q: How thick are the coasters? (with and without rubber tips)

I would say approximately 3/16" and a 1/4" with the rubber bumper.

Q: What size or dimension is best for a glass or mug? Honestly just want them for decorative purposes but still big enough for a glass

size 3-3.5'',about 8-9cm .Bottom diameter less than 9 cm cup, can be placed on top . size 3.5-4",about 9-11cm .Bottom diameter less than 11 cm cup, can be placed on top .