Where is the best place to buy Japanese silk?
I am currently using korean made. How does it compare to Japnese?

Silk King Studios only sells silks made in Japan.

My vote for Japanese silk too...

LOL --- For years my wife did not know that we import silk from China to Alabama, then ship it to Singapore. From there it goes to Japan to become Japanese silk. On page 8 Harold Rice tells you that China silk is the best. (Today it is even better because of the good 2mm hems.) He did not tell you that he could not get it back then. Things have changed since the 1980s.

Does anyone make polka dot silks maybe 30" square, similar to paul potassy sympathetic silks,

Paul Potassy Sympathetic Silks, that silk or ladies dress material is usually only available from very high end fabric stores. I doubt you will find it already hemmed.

And they are fantastic! The selection of colors of their Spectrum Silks cannot be beat.

Japanese silk has changed over the years. At one time, there were four major silk manufacturers in Japan. When I last checked, there was only one and why imported the silk cocoons from China. So I guess it is Japanese/China silk.

Be aware that Momme is only a measure of MASS and NOT QUALITY. Higher momme can mean looser weave to add mass. That has its own set of problems.

Silk King Studios have fantastic silks. They are more expensive, but you get what you pay for and you really want the silks to look good from stage.

As a side note, if you visit the Henry Ford Greenfield Village in Dearborn Michigan (which I recommend to everyone!) they have a working silk loom that they demonstrate and explain the process of weaving silk. Henry Ford wanted to skip the importing stage and make his own silk, but the silk worms only eat Mulberry leaves and they couldn't grow enough fast enough in Michigan to keep them fed! Poor silk worms gets boiled alive in the process.... but such is the circle of life.