Vivo S1 is available in 2 color variants - Diamond Black & Skyline Blue.
Vivo S1 has 6.38 inches of AMOLED Full HD plus display. It is further protected with Corning Gorilla Glass 5 level of protection. The mobile has a 90% screen-to-body ratio and has 19.5:9 aspect ratio. Vivo S1 offers 404 PPI of resolution.
Yes, Vivo S1 has dual 4G support. You can use 2 4G network sim cards at the same time.
No. Vivo S1 is not a waterproof mobile phone. However, plenty of covers available for the mobile which can protect from sudden water splash.