Many thanks Mauriz. The image you posted of Queen Victoria on the left hand side does appear to show the Oriental circlet tiara with greater detail than the image I posted. Many thanks for the image. I think your image is probable proof that the two tiaras are the one and the same.
The Irish Library source says that the portrait was painted in 1854. http://www.libraryireland.com/irishartists/stephen-catterson-smith.php I will have to find (later) where I read that the portrait was painted in 1854 to commemorate HM's visit in 1849, We all know I might be incorrect!