San Francisco Frontiers - Hamilton keeps nose stud after showdown with Grand Prix 'bling' police

The decision to enforce rules on jewellery and underwear had stirred controversy in the pre-practice press conferences.

Hamilton threatened to spend the weekend seeing the sites of Miami instead while Sebastian Vettel said he thought the English driver was being "targeted".

Hamilton was wearing three watches, a bracelet, necklaces and a nose stud for the press conference and said he would need to "chop my ears off" to remove his earrings.

"I couldn't get any more jewellery on," he joked.

"We have spare drivers, so we're ready and prepared for the weekend. There is lots to do in this city so, I'll be good either way!" Hamilton said of the prospect of being forced out of the race.

Yet, after making his threat, he removed most of his jewellery, including the earrings, for the practice session but scored a small victory with an exemption for the nose stud.

That exemption was reported to be for two races.

Vettel showed his feelings by wearing underpants over his race suit as a sign of protest.

Race director Niels Wittich wrote in his guidelines for Sunday's race that driver jewellery and underwear should be checked, to ensure they comply with the FIA's fire-proof safety standards.

In his race notes, Wittich wrote: "Metallic objects, such as jewellery, in contact with the skin can reduce heat transmission protection and thus may increase the risk of burn injuries in the event of a fire."

Vettel said the actions appeared to be aimed at Hamilton.

"Probably, at this stage, it's more of a personal thing and I feel in a way targeted to Lewis," said Vettel.

Aston Martin's Vettel suggested the topic was trivial.

"We spoke about underpants as well, but really is that the most exciting thing we can talk about?" he asked.

"There's a concern for safety, obviously, if you have stuff -- and if the car does catch fire it would be unpleasant.

"But, on the other hand, to some degree it's personal freedom and we are old enough to make our choices outside the car... We should be old enough also to make our choices inside the car."

Hamilton said his jewellery had never been a problem.

"It's platinum so it's not magnetic and it's never been a safety issue. I've had so many MRI scans, for example, and I don't have to take out my platinum ones..."

He said he wore three watches because they were set to three different time zones.

Two drivers were sanctioned at last weekend's Monaco E-Prix in similar incidents, Pascal Wehrlein and Mitch Evans both taking penalty points on their 'super licences' and receiving fines of 1000 euros ($1050) each for wearing metal chains during qualifying.

V.Mitchell--SFF