Gotras and Navratnas used by Brahmins/Hindus

[bansy]

I was searching about Brahmins and came across these two fascinating areas in Hindusim :

Can anyone explain more about the significance of
1) Gotras (Caste Lineage). There are supposedly 8 gotras in the Brahmin caste. So if one traces their gotra, they are tracing back their lineage....a bit like going from in reverse direction in the Drama Wheel.

2) Navratnas (9 star jewelry) worn by some Hindus.

Someone of Indian background may know more about this.