Before I started a geology blog, I used to sporadically blog about geology over at
Skepchick. These days, I blog here at Georneys about geology, and I blog over at Skepchick about other skeptical and scientific things, such as
why I am thankful for science. Occasionally, I will re-post some of my old geology posts from Skepchick. I will also sometimes cross-post on both blogs.
The post below originally appeared on Skepchick in 2006
here. Since I recently blogged about
my favorite rock peridotite, I think it is timely to revisit this Skepchick post. The Skepchick post appears below with minor corrections.
 |
| A peridot engagement ring. |
As a geologist and a skepchick, I’d like to debunk a popular myth: a diamond is
not forever. This clever phrase was
coined in 1948 as a marketing slogan for DeBeers, but I cry that it’s false advertising. Diamonds, formed at high-pressures deep within the Earth, are metastable in the low pressures at Earth’s surface. Over many million of years, the carbon atoms in the gemstones will rearrange, converting the diamonds into graphite. Pencil lead, essentially.
A real forever gemstone? Maybe zircon. There are zircons in places such as western Australia that are
over four billion years old. Forever is a long time, though, and even zircons eventually degrade. Blue zircons can make really beautiful gemstones, though.
