Indirect sign of quality silk fabric, if you buy it in a foreign country, is its price. $ 25-39 cheaper things made of natural silk is not worth while, as the price of rayon will be several times smaller.
On the surface of natural silk fabric can notice the uneven structure of the thread, the place of its compounds irregularities. The surface of the artificial fake polyester is smooth, flawless, no uneven and rough, uniform tone and color.
Depending on the quality, density and structure of the fabric weave, silk can be very light, airy and soft or hard to the touch and heavy. Natural light fabric may crease, but immediately and smoothed. On polyester will remain tough creases. Silk high quality almost crushed.
Indicator of naturalness is gloss surface of the material. For example, in the manufacture of Thai silk used longitudinal and transverse yarns of different colors, which gives the fabric a colorful tide when the angle of illumination and radiance at the folds. In artificial leaf smooth white patch in tissue does not depend on the lighting.
The most accurate way to check quality - the use of fire. Of course, it is not necessary to burn the thing is enough to take a small piece of thread and bring it to a candle flame. Silk - protein compounds, therefore burning thread would smell singed hair or fur, but artificial - nothing, it just melted.