Nikolas Gregory Studio's conceptual Ripley kit encourages users to swallow and excrete their own biologically customised piece of jewellery.

The Ripley kit would use the body's natural digestive processes to tailor a ring. It contains a collection of materials including edible abrasives – such as almond shell and corn husk – polishing compounds, natural food colouring and a jewel-encrusted gold ring.

The user would ingest the materials, and as the ring passes through the body it would gain a "distinctive patina" created by stomach acids and whatever was recently eaten.

After consumption, the owner would excrete the jewellery as "a very personal ring for your loved one".

"While citric acid from fruit and soda tends to pit the base material, lactose and calcium aggregate and deposit on the surface," explained Nikolas Gregory.

"Not surprisingly, it has been found that popcorn and almonds produce a specular finish while banana, apple and pasta leave the surfaces muted," he added.

"Once the ring has been polished, the fecal matter will begin to harden, the dyes will colour the jewels on the ring's surface."

The user would then have to retrieve the jewellery after expelling the material.

Gregory designed the concept for a future when food has been replaced by non-agricultural alternatives, and the human digestive system is under-used.

"In the interest of re-purposing an antique mechanism – before it is 'evolved' out of existence – I imagined a manufacturing process which might rely on the old human 'machinery'," he said. 

"I can see this kit as both a highly personalised luxury product as well as an amusement, a kind of parlour game in which people can mix and match or compare results," he added.

According to the designer, all of the kit's elements would be natural and organically grown, and are also safe for the environment. Although the process has not been tested in real life, the designer assures that its ingredients are common to everyday diets.

"I imagine this will become an acquired taste or, perhaps better, a practice which takes time to get used to but ultimately quite simple to contemplate," he said.

Icelandic fashion designer Sruli Recht has also experimented with biological jewellery, creating a ring decorated with a slice of skin taken from his own belly.