I remain quite sceptical about - Queen Mary's Warwick Star Brooch - Queen Mary's wedding gift to the Duchess of York in 1923 ("a sunburst diamond brooch pendant, the stones being set in the form of a rising sun") - and the sunburst pendant worn by QEQM (then Duchess of York) on the picture published by Ursula's website being one and the same jewel.
Reason for my scepticism is that the pendant worn by the Duchess of York might look as a sun, but not as a rising sun. A rising sun would include only a partial view of a sun, not a full sun.
To explain clearly what I mean, the following jewels could be described, IMHO, as "rising suns" (pictures from the web, these jewels are not from specific royal collections, I only include them for illustration purpose):