That is the idea. The Braganza Family has so many beautiful jewels but they are never discussed.
How interesting what you are telling. All the information I have (including the last book about the Portuguese royal jewels) points to this to be the engagement ring (anel de noivado in the book). Also I never heard anything about a ruby ring nor saw the Duchess wearing one in the last years which does not mean that it does not exist (Im not doubting of your word). It would be nice to see a picture of it.
However, now that talk about it, it is in fact possible the existence of another engagement ring. This ring could only be made after TRH know their wedding day so it would not be possible for HRH The Duke to propose with this ring. If so what can we call to this?
The sapphire ring is another story ... l will talk about it later.