It depends upon the family actually.
Some think that mangnis/engagements are considered as bad luck in the family so they just do the baat pakki and set a later date for the wedding. No rings are exchanged.
Some consider big and grand mangnis/engagements as bad luck in the family so they just have a very small intimate gathering with only the family. Rings are exchanged but the parents do the ceremony not the bride and the groom. Sometimes the groom isn't even present at the ceremony.
Rings are generally not considered as necessary as they do in a non-desi environment. The groom gets a hefty watch instead, occasionally a golden one but I have seen that the grooms prefer the silver ones.
Some go all out with a big party with all the trappings.
And, yes engagement is called 'mangni' and fiance is 'mangaythar' in Urdu and 'mang' in Punjabi.
Oh ! really interesting to know that !!!!!!!!
one day i have heard that rings its something in culture of europeens not muslims and we should not imitate them , even if we do , we just consider it as gift not as link between the couple , because they beleive that the ring which unite them , so if they loose it , its bad thing !
but we , we must beleive that Allah who unite us not a ring !!!!
thanks for explaining to me