Apparently there was some big wedding in London recently. I can't say I watched it. I was probably still too apoplectic over why Mr Pollock chose not to yellow-card a single Blues player earlier that evening. Or maybe I just didn't care a jot.
But it does allow me to segue smoothly into something that, as well as being wedding-related, is also chemistry-related, thereby making it much more interesting.
Last month, the Disputes Tribunal dismissed an appeal against a ruling made last November in which a customer of an Auckland jewellery store was refunded the cost of a $5600 "white gold" engagement ring because he was not informed that the "white gold" was, in fact, rhodium-plated gold alloy. Such rings require frequent replating, because the rhodium wears off, and the customer was not told this.
There are so many places I could start with this story. But let's begin with "white gold".
You'll have noticed I've enclosed this in quotes thus far, because there is no such thing as white gold. There is pure gold, which is always a beautiful, um, gold colour, and then there is impure gold, which gets sold as "white gold", an oxymoron if ever there was one. Mind you, impure gold sounds a little harder to market than "white gold".
So, knowing that white gold doesn't actually exist, what then is this stuff that gets sold under that name? It is, in fact, many things. It can be gold alloyed with other metals such as nickel, palladium or manganese, or it can be a rhodium-plated gold alloy.
I'm guessing there may be more than a few of you who haven't heard of rhodium. It's an element that was discovered in 1803, and named after the Greek word for rose, owing to the red colour of a number of its compounds. It is the most expensive of the so-called "precious" metal elements on the periodic table (gold, silver, palladium, platinum, ruthenium, osmium and iridium are the others) and is currently one and a-half times the price of gold.
So, if money is no object when it comes to impressing your intended betrothed, why not then have a ring made of pure rhodium? Well, it turns out that rhodium is quite hard and brittle, and therefore difficult to work. Gold is much softer and more malleable, and this, coupled with its beautiful colour, makes it the precious metal of choice for jewellery.
In fact, pure gold is rather too soft to be used in some types of jewellery, and this is the reason it is often mixed with other metals. Such mixtures come in a variety of colours; not only white but purple, rose, blue, black and green gold are all known, which to me kind of defeats the purpose - why would you want gold that doesn't look like gold? Surely the whole point of having a gold ring is to see the gold colour?
It seems this question didn't arise for the kids at the big London wedding - their ring was made of "Welsh gold". Of course, "Welsh gold" is no different to the gold they dig out of the ground at Macraes. But somehow, I don't think that "colonial gold" was ever going to be an option for their ring.
• Dr Allan Blackman is an associate professor in the chemistry department at the University of Otago.