I have used URSHII Cotton thread (DK) in the featured coasters in Sage Green and Burnt orange shades.
Yardage : 80-90 m (88 - 98 yards) per 50g

To make the coaster in 2 variants you need:

If you carry the yarn at the back - then you would require approximately 21 yards of Main color and 14 yards of Contrast colored yarn.

If you want to make a Fringed Version: requires approximately 16 yards each of Main and Contrast color yarn.