I'm interested in finding a tool that I've heard referred to as a Champagne "diamond." Can you tell me whether it is still in production, and is it all that odd a tool?
It is both: odd and also, I believe, still in production. The item you refer to is also commonly called a Champagne "star," a reference to its shape. Personally, I think it more closely resembles a tarantula, with four "legs" instead of eight and not as hairy. It's designed to facilitate removal of the mushroom-shaped cork from a bottle of sparkling wine. Screwpull, the prominent corkscrew-maker, has one, as does kitchenware company Le Creuset (though Le Creuset's model is no longer part of the company's regular assortment in Canada). Check out Amazon.ca and search for those companies and include the words "champagne star."
Pulling that cork can be tough because it's highly compressed into the neck to help hold back the high carbonation pressure. If the wine has been standing upright in the dry condition of a fridge for months, the cork also can desiccate, which may render the extraction even more difficult.
A Champagne star comes to the rescue with its claw-like grip. Unshackle the cork by removing the wire cage, push the four legs of the star down over it until they press firmly into the cork, then twist.
If you drink Champagne only rarely (and for that I offer my condolences), or you simply prefer not to invest in more kitchen-drawer clutter, there is a cheaper, tool-free way to accomplish much the same thing. Untwist and loosen the wire cage over the cork – but leave the cage where it is, covering the cork. Then, with your non-dominant hand (left if you're right-handed, right if you're left-handed), clasp the the cork and (loosened) cage. The cage will provide extra grip against the otherwise slippery cork. Then open the bottle, but not without first adhering to the following advice.
Never let go of the cork and cage; that's a no-no. With your dominant hand, twist the bottle rather than the cork. And don't let go of the cork as it emerges from the bottle. It should remain in your fist, not become a ballistic missile that takes out a lighting fixture or someone's eye. That's the suave and safe way to pop Champagne. Leave the flying corks to hip-hop artists cruising in stretch limos.
The Flavour Principle by Lucy Waverman and Beppi Crosariol (HarperCollins) won top prize for best general English cookbook at the 2014 Taste Canada Food Writing Awards.