At a local craft fair, a vendor had a set of crocheted coasters that were white with a peppermint stripe border. Since time was tight, I opted to buy them for my mom. I joked with the woman that I could probably make them, but didn’t have time, plus I didn’t know how to do the border. And, because I didn’t know how to do the border, I couldn’t make a bunch as gifts for my mom’s friends 
Fast forward to winter break… my mom’s color scheme includes a lot of gray, and she just happened to have gray and white cotton yarn on hand, so guess what I learned how to do? 
One is slightly larger due to a different tension on the border, but Mum still loves them!
Basic Instructions for 1 Coaster: US Terminology
I used cotton yarn with an H hook, but worsted weight acrylic would also work. You will need 1 color for the main part of the coaster, and 2 colors for the edging.
Using your main color, start with a magic circle (or chain 4, slip stitch to join into a ring).
R1- Ch 3, 9 dc (10), join with SS to top of ch 3
R2- Ch 3, dc in same space, 2 dc in each stitch around, join with SS to top of ch 3 (20)
R3- Ch 3, 2 dc in next stitch, (sc in next stitch, 2 dc in next stitch) X 9, join with SS to top of ch 3 (30)
Fasten off and weave in ends. (Note: If you are using your main color as one of your border colors, you don’t need to fasten off.)
For edging, I used this tutorial:
