Add to Cart Compare Quick view So Silk Papers 10x13 Envelopes, 500 for $526, 92lb Cover C1S, Black Print, MSRP: Now: $526.00 Was: So...Silk 10x13 envelopes are finally available. Please ask about matching letterhead, different stock colors or other types of envelopes.SO...SILK papers come in 8 colors with an iridescent visual effect, a smooth finish and weights from 88 lb. C1S text... MSRP: Now: $526.00 Was: Add to Cart Compare Quick view