Brilliant Eugenie! I read this post and it inspired me to check an amber tray and candlesticks I have for an RD Number, and lo and behold there it was on the top side of the tray RD 698049! The candlesticks are stylistically matched perfectly with the tray and a Queen's Choice bowl which I already owned, the glass even feels the same.
While surfing around the GTS Mysteries section I then spotted the same set in Amber, Blue and Frosted/Satin Uranium, the Amber images are the actual set I purchased a while back, and there with the blue items is a Queens Choice Bowl in blue and what appears to be a ring holder in blue exactly the same as yours!
http://www.glasstrinketsets.com/Gallery/thumbnails.php?album=153 (GTS Mystery 148)
So there we are, it seems Bagley DID make a full Dressing Table Set / Trinket Set / Vanity Set in the Queen's Choice pattern, comprising at least a Tray, Powder Pot, Candlesticks and Ring Holder.
I will upload some pics of the RD Number and Set asap.