Navy Blue Envelopes – 100gm Paper – All Sizes In Stock – Lowest UK PriceOur top quality 100gsm Colorplan (Imperial Navy Blue) envelopes are fantastic quality with a continuous colour depth inside and out. Because we stock these navy blue envelopes in all our popular sizes, you can get these delivered in as little as 1 working day. Available now in gummed diamond flap formats as part of our GF Smith Colorplan collection of luxury quality coloured envelopes.