Almost every decade has a signature sari. In the 1920s it was the chiffon with a zari border (pics 1 and 2 are from 1924 and 1931). The borders were generally small and stitched onto French chiffons. In the case of lighter Indian handlooms like Chanderis the zari was woven into the sari. Towards the middle of the 30s and later and carrying on to the next decade, the borders are often heavier and of brocade while the sari remains a light chiffon (or any other light material).
E.g.s: Pic 3: Maharani Kanchan Prabha Devi [X], Pic 4: Maharani Gulab Kunverba Sahiba, 1935, Pic 5: Menakaraje of Cooch Behar in the mid 30s, Pic 6: Rajmata Krishna Kumari in the mid 30s. While the women here have their pallu draped over the head (partly because this was common amongst Indian royals by this decade), this was less common by the end of the 1930s.
Sometimes a second band of brocade (or zari) was added to the pallu as in Pic 4.
For a circa 1940 example, see a previous post.