Onyx is a patented yellowish white opaque glass with raised silver daisy decorations. A few rare pieces were made of rose, amber, orange, or purple glass but the flower pattern in all colors and shapes stayed the same here are a few examples of flower pattern in 2 colors
http://www.liveauctioneers.com/item/8491301 http://www.cbantiques.com/SugarShakers/sugshkfindlay.html Floradine and Onyx, although they are the same pattern, are easy to tell apart. Floradine has a red base color and Onyx can be numerous colors, including white, yellow, amber, maroon or silver But again all in the same shapes & daisy pattern.
Your piece is beautiful & does appear to be an older piece but would need to search to determin maker (not an easy task
