Overview:

Burning a thread of the material purported to be silk is a means of checking if it is pure silk or not. Pure silk will crumble to ash, whereas synthetic fibres will curl up when burnt.
There are three main categories of silk:
One ply silk has one single weft against one warp creating soft fluttering fabric. This is very light weight, comfortable to wear, suitable for making shirts, blouses, and light weight clothing designs.
Two ply silk has double weft against one warp creating a firmer fabric, strong and a little more stiff. It is suitable for formal wear, jackets, and dressy outfits.
Four ply silk has four weft threads against one warp producing a very thick and stiff almost coarse fabric. It is popular for men's suits, interior decorations, and furniture.
Good quality silk is fine and smooth to the touch. The colour will be uniform all over the textile and will not wash out as only dyes of the very highest quality are used.
Though Thai silk is durable, it is not as tough as cotton or linen, therefore dry cleaning is recommended, so as to retain the original texture.
Thai silk can be washed in lukewarm water but only with the mildest soap, then rinse the silk in vinegar to retain its original luster and allow it to drip dry in the shade. Thai silk should be ironed on the inside just before it is dry or else put a damp cloth over the silk and iron.
When you hold a piece of 100 percent silk up to the light, the overall colour tone will change depending on the angle of light. With imitation silk, regardless of what light angle you hold it in, it shines white.
There is a big difference in price between the 100 percent silk items and the imitation items.