Have a look at this
http://i1207.photobucket.com/albums/bb473/Royal_Gossip/Royal_Jewelry_and_Tiaras/britishroyalfamilycollectiontheagelessdiamondexhibitlondon.jpg
the rundell 
Look at the Queen of Malaysia!

I think she is wearing the rundell tiara or not??? It is missing since Queen Alexandra died -because of the lack of a testament.
http://i1207.photobucket.com/albums/bb473/Royal_Gossip/Royal_Jewelry_and_Tiaras/Malaysiantiara-rundell.jpg Papyrus Tiara:

This tiara was made in 1925. It was given as a wedding present to Lady Elizabeth Bowes-Lyon. S
It is a tiara with papyrus-shaped mounts framed in scrolls separated with palmettes. The diamond trails arch above, surmounted by diamonds and a pearl.
Serena Stanhope wore it at her wedding with Viscount Linley, the son of the late Princess Margaret, Countess of Snowdon.
http://i1207.photobucket.com/albums/bb473/Royal_Gossip/Royal_Jewelry_and_Tiaras/England_serena-stanhope_papyrus-tiara.jpgI love this emerald tiara
Iveagh Tiarahttp://i1207.photobucket.com/albums/bb473/Royal_Gossip/Royal_Jewelry_and_Tiaras/green-tiara.jpgThis shows Queen Mary wearing it:
http://i1207.photobucket.com/albums/bb473/Royal_Gossip/Royal_Jewelry_and_Tiaras/iveaghemeraldtiaraqueenmary.jpgI am not sure if it is still in the posession of the BRF. This Tiara was designed by Albert, the Prince consort, for the Queen. It is being said that it is now owned by an un-named relative of Queen Victoria.

But Mary wore it, so...
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I found this list at the Royal Magazine (fan page):
Windsor Tiara's1. Queen Alexandra’s Russian Kokoshnik
2. Girl’s of Great Britain and Ireland Tiara
3. Strathmore Rose Tiara
4. Queen Mother’s Papyrus (Lotus Flower) Motif Tiara
5. Mrs. Greville’s Boucheron Honeycomb Tiara
6. Delhi Durbar Tiara
7. George IV Diadem
8. Vladimir Tiara
9. Queen Mary’s (Hanoverian / George III) Fringe Tiara
10. Queen Mary’s Lovers Knot
11. Oriental Circlet
12. Queen Elizabeth’s Sapphire Tiara
13. Burmese Ruby Tiara
14. Sarah, Duchess of York’s Tiara
15. Brazilian Aquamarine Tiara
16. Queen Mother's Cartier Aquamarine "Pine" Tiara
17. Persian Turquoise Tiara
18. Snowdon Floral tiara
19. Greek meander Tiara
20. Princess Anne’s Antique Festoon Tiara (given from ‘World Wide Shipping Group’)
21. Countess Sophie’s Wedding Tiara (Regal Circlet – honeysuckle motifs)
22. Countess Sophie’s Cluster Tiara (Flowers/Buttons)
23. Countess Sophie’s Aquamarine Centre Tiara
24. Princess Alexandra’s Tiara
25. Kent Festoon Tiara
26. Princess Marina’s ‘City of London’ Fringe Tiara
27. Cambridge Sapphire – Cluster Tiara
28. Kent - Queen Mary’s Small Diamond Bandeau
29. Iveagh Tiara
30. Gloucester Turquoise Tiara
31. Gloucester Emerald Bandeau
32. Gloucester’s Honeysuckle Tiara
33. Gloucester Diamond Bandeau necklace( diamond necklace also been worn as Tiara)
34. Princess Marie-Louise Cartier Indian Tiara
35. Lady Ulster’s wedding tiara
36. Queen Elizabeth’s Mystery Tiara
37. Princess Anne’s Mystery Tiara
38.Queen Mother’s scroll tiara (worn by Kate on her wedding day)
Not seen in decades (or broken up):39. Queen Alexandra’s ‘Rundell’ Tiara (Prince Albert’s Wedding Gift)
40. Nizam of Hyderabad Tiara
41. Queen Mary’s Wedding Gift from Queen Victoria ( said to be broken up to create the Queen Mary’s Fringe Tiara)
42. County of Surrey Tiara
43. Teck Circlet-Teck Circlet
44. Queen Mary’s Diamond Lozenge Tiara
45. Queen Mary’s unidentified Diamond Filigree Tiara
46. Queen Mary’s diamond Leaf tiara
47. Queen Mary’s 1902 Boucheron Diamond Loop Tiara
48. Ladies of England Tiara
49. Empress Marie Feodorovna Sapphire Bandeau
50. Princess Anne’s unidentified tiara (21st Birthday Sitting)
51. Queen Mother’s scroll tiara
52. Queen Elizabeth’s two -hidden Sapphire tiaras.
53. Princess Alice (of Battenberg’s) Tiaras
54. Duchess of Kent Aquamarine and Turquoise Tiaras (possible loans)
55. Queen Victoria’s Regal Circlet
Sold:56. Queen Victorias Strawberry Leaf Ruby Tiara
57. Princess Mary’s Diamond Diadem
58. Princess Mary’s Fringe Tiaras (2) (Queen Mary and Lord and Lady Inchcape)
59. Princess Mary’s Honeysuckle Tiara
60. Princess Mary’s Butterfly Centre Tiara
61. Princess Mary’s Diamond scroll and cluster circlet.
62. Princess Mary’s Emerald Tiara
63. Poltimore Tiara
64. Cambridge Sapphire – 7 Prong tiara
65. Princess Marina’s Pearl and Diamond Circle Tiara
That's a VERY loooooooooooong list!