Well spotted Dave! The tiara worn by Rachel, Countess of Dudley for the Empire Ball in Dublin in early 1905 is reminiscent of the Girls of Great Britain and Ireland tiara given to Queen Mary as a wedding gift in 1893.
If the report in 1900 about Lady Edith Ward, Lady Wolverton, wearing a "crown" made by Boucheron was accurate and that the tiara in question was a wedding gift, I doubt if it is the same one. Lady Edith married in 1895. I think it is unlikely that her sister-in-law, Rachel, would have borrowed the tiara to wear in Dublin in 1905. But, as we all know, anything is possible.
The only item resembling a tiara in the list of Lady Edith's wedding gifts was the jewel given to her by her mother, Georgina, Countess of Dudley, but the press may have been referring to other jewels left to Edith by her father. Perhaps she only commenced wearing some after she married and so people assumed they were wedding presents. I have yet to find a list of those jewels.