San Francisco start-up Crave has launched a stainless-steel vibrator that can be worn as a necklace and charged via a USB port on a computer (+ slideshow).

Co-founded by entrepreneur Michael Topolovac and Royal College of Art graduate Ti Chang, Crave created the Vesper vibrator as a design-focused stimulator rather than a novelty item.

"For lack of a better term, the 'sex toy' category has historically been overrun by novelty products," Chang told Dezeen.

"Being free of that legacy, we are able to approach the design of our products like one might approach other modern products, and use materials and design thinking to support a rich experience for the user."

The 9.65-centimetre-long vibrator can be worn on a chain around the neck as a metallic pendant, or removed from the chain and kept in a drawer a home.

"In the case of Vesper, I was intrigued to explore, in a fun way, the tension between that what is private and public," said Chang.

"Not everyone is going to want to wear this out – some women love it as a piece of jewellery with a naughty secret, for others it is a symbol of sexual empowerment to wear their pleasure openly."

"At the same time we recognise that it is a totally personal decision, so the design of the necklace is intended to be removable," Chang added.

Designed for external use only, its minimal case includes just one button to turn the device on, change between the three speed options and a pulse setting, and turn it off.

The body and tip of the slim vial-shaped device are made from polished stainless steel, shaped using computer numerically controlled (CNC) machining.

The chain and cap are also made of stainless steel and finished with a choice of silver, rose gold, or 24-karat gold nickel-free plating. An all gold-plated version is also available.

Inside, a small circuit board controls custom-machined and silicone-moulded parts.

The decision to make Vesper USB rechargeable was driven by environmental and convenience considerations.

"It is simply much better for the environment and for the user experience, removing the hassle of replacing batteries," Chang explained. "USB recharge-ability also makes the product travel friendly – users no longer have to think about packing chargers, adapters etc."

Vesper is in production and will be ready to ship in early September. It is currently available to pre-order with optional free engraving – quoting Charles Eames, the example given is: "Take your pleasure seriously".