# What shows up besides metal in X-ray luggage screening? **URL:** \ **Category:** Factual Questions\ **Created:** [December 28, 2004, 6:16pm UTC](https://boards.straightdope.com/t/what-shows-up-besides-metal-in-x-ray-luggage-screening/281966 "2004-12-28T18:16:38Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Limbo\_Donni](https://avatars.discourse-cdn.com/v4/letter/l/5f8ce5/32.png) [@Limbo\_Donni](https://boards.straightdope.com/u/Limbo_Donni)\ **Post date:** [December 28, 2004, 6:16pm UTC](https://boards.straightdope.com/t/what-shows-up-besides-metal-in-x-ray-luggage-screening/281966/1 "2004-12-28T18:16:38Z")
In this month’s Ellery Queen Mystery Magazine, there’s a story where a detective says real rubies on an antique robe would show up but not glass imitations. 1. Is that true? 2. What else shows up besides metal and rubies? ---
**Author:** ![Limbo\_Donni](https://avatars.discourse-cdn.com/v4/letter/l/5f8ce5/32.png) [@Limbo\_Donni](https://boards.straightdope.com/u/Limbo_Donni)\ **Post date:** [December 29, 2004, 4:17am UTC](https://boards.straightdope.com/t/what-shows-up-besides-metal-in-x-ray-luggage-screening/281966/2 "2004-12-29T04:17:21Z")
I don’t how rubies would show up anyway. If they are too porous to stop red light, then they’d be no barrier to xrays, would they? ---
**Author:** ![TJdude825](https://avatars.discourse-cdn.com/v4/letter/t/dec6dc/32.png) [@TJdude825](https://boards.straightdope.com/u/TJdude825)\ **Post date:** [December 29, 2004, 4:30am UTC](https://boards.straightdope.com/t/what-shows-up-besides-metal-in-x-ray-luggage-screening/281966/3 "2004-12-29T04:30:37Z")
IIRC, cheese shows up pretty easily, and can be mistaken for a bomb. So don’t pack cheese in your carry-on, I guess. ---
**Author:** ![SavageNarce](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@SavageNarce](https://boards.straightdope.com/u/SavageNarce)\ **Post date:** [December 29, 2004, 1:05pm UTC](https://boards.straightdope.com/t/what-shows-up-besides-metal-in-x-ray-luggage-screening/281966/4 "2004-12-29T13:05:42Z")
Obviously, things other than metal show up in x-rays - that’s why x-rays are such a handy diagnostic tool in medicine. Rubies are a compound of aluminum and oxygen (Al203), and perhaps the aluminum would make them show up more clearly than glass on an x-ray - but never having x-rayed a ruby, that’s just a WAG. ---
**Author:** ![Bewildebeest](https://avatars.discourse-cdn.com/v4/letter/b/779978/32.png) [@Bewildebeest](https://boards.straightdope.com/u/Bewildebeest)\ **Post date:** [December 29, 2004, 1:15pm UTC](https://boards.straightdope.com/t/what-shows-up-besides-metal-in-x-ray-luggage-screening/281966/5 "2004-12-29T13:15:01Z")
A couple years ago I had jury duty in Greenbelt, MD. After I went through the security screen I looked back and saw the image of my backpack on still-store. I could clearly see the banana I’d brought for lunch, as well as a book. [Insert Python joke about villians armed with fresh fruit here.] ---
**Author:** ![Bewildebeest](https://avatars.discourse-cdn.com/v4/letter/b/779978/32.png) [@Bewildebeest](https://boards.straightdope.com/u/Bewildebeest)\ **Post date:** [December 29, 2004, 1:25pm UTC](https://boards.straightdope.com/t/what-shows-up-besides-metal-in-x-ray-luggage-screening/281966/6 "2004-12-29T13:25:07Z")
You might want to investigate X-ray crystallography. You can determine the structure of a crystal by X-ray defraction. Glass and ruby would probably both show up, but differently. ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [December 29, 2004, 5:04pm UTC](https://boards.straightdope.com/t/what-shows-up-besides-metal-in-x-ray-luggage-screening/281966/7 "2004-12-29T17:04:26Z")
> [@Limbo Donni](#): > > I don’t how rubies would show up anyway. If they are too porous to stop red light, then they’d be no barrier to xrays, would they? The ability to transmit or absorb electromagnetic radiation has little, if anything, to do with how porous a substance is. Rubies are an ordered crystal matrix that will defract x-rays in a specific pattern.