I’m sorry I can’t do this from an Indian point of view, but I can do it from a European perspective.

The true story of crowns started with the Greeks and Romans. The Greeks were fond of using laurel wreaths as signs of victory. This was appropriated by the Romans as a sign of military conquest, and a more ornate golden one during the Empire as a sign of royalty. However, something changed by the Late Empire- emperors were more prone to seeing themselves as a military man, instead of the princeps or a Greek-style despot. This tradition was carried on in Western Europe beyond the Empires collapse.

To recap at this point, where we are is-

Gold=good

Needs to be able to be on a helmet

Circle=good

And so the circlet was born. (I must put in a disclaimer here, I am much less sure of the previous than i am of the following)

The circlet was a band of gold placed either on a helmet or on ones head. At this stage, a couple of people had the idea of putting gems on a crown to make it look cool and shiny. I’m not sure when exactly this is, however by the time of Charlemagne one can see it in its full glory. Here we see a divergence between basic circlets (such as the Lombard Iron Crown [assumed to be from the 9th century but actually from the 12th]) and what became known as closed or imperial crowns (such as the Crown of St Steven). A closed crown was initially having an arch or two above a circlet, which later included velvet, which made it look like a ‘turban’. More and more rulers chose to gain status points by adopting closed crowns, which brings it to the ornate state it is today