Gae-tan! Today's word is "gem"

Gae-tan! Today's word is "gem"
 An English vocabulary book for games that you can learn by looking at them, or "Gae-tan!" for short. Today's word is "gem". Meaning jewels. Isn't it jewel? If you thought so, you're right! Gem and jewel are words that have the same meaning of "jewel". But there are subtle nuances, and if something has a strong stone aspect, it's like a gem....

The linked article is in Japanese.