Mrs BigD, best thing to do is to take them to a jewellers who will, for a small fee, give you a value for them in writing. Then you can keep that with your insurance details. That's what I did with a diamond ring I inherited.
Shifty looking man in dodgy overcoat comes runnong up the street, seeing MrsD. He thrusts a handful of jewellery at her and says "'Ere, take this!" and pegs it down an alleyway closely followed by 2 policeman. Mrs D shuffles surreptitiously up the road to the corner and runs off.
definatley need valuing and written valuations for insurance purposes.
i have a cartier bagle which sounds like the second one you describe and it is listed sepaeratly on my contents insurance. (the most expensive piece of jewllery i own dh brought it when we sold our house and had already brought the new one so got to keep the extra. cost more than my engagement and wedding ring together.)