Rubi (ルビ - Syllabaries )

In Japanese sentences, small hiragana syllabaries are sometimes written above or the side of kanji (Chinese characters).

This hiragana syllabaries are called "hurigana" (振り仮名), and is also called "rubi" (ルビ).

The etymology of "rubi" is just ruby, a kind of gemstones.

In British publishing industry, font sizes have given names of gemstones.

For example, Diamond is 4.5 points, Pearl is 5 points, Ruby is 5.5 points, and Emerald is 6.5 point.

In the Meiji period, the main font size on Japanese newspapers was 10.5 points, and the font size of hiragana syllabaries was 5.2 points.

Since the size was similar to the size called Ruby, we have come to use the term "rubi" (ルビ) to mean the hiragana (or katakana) syllabaries.

ルビ

日本語の文章では、漢字の上や横に小さく振り仮名をつけることがあります。

この振り仮名のことを、「ルビ」と言うことがあります。

「ルビ」は、宝石のルビーが由来となっています。

イギリスの出版業界では、活字の大きさに宝石の名前が付けられていました。

例えば、ダイヤモンドは4.5ポイント、パールは5ポイント、ルビーは5.5ポイント、エメラルドは6.5ポイントです。

明治時代、日本語の新聞記事に使用された活字のサイズは10.5ポイントで、その振り仮名に使われた活字のサイズは5.25ポイントでした。

このサイズがルビーの5.5ポイントと近いことから、振り仮名のことをルビと呼ぶようになったというわけです。

• In Japanese sentences, small hiragana syllabaries are sometimes written above or the side of kanji (Chinese characters).
• In Japanese sentences, small hiragana syllabaries are sometimes written above or to the side of kanji (Chinese characters).

  "sometimes written above or beside kanji" would also work.

• This hiragana syllabaries are called "hurigana" (振り仮名), and is also called "rubi" (ルビ).
• This These hiragana syllabaries are called "furigana" (振り仮名), and is are also called "rubi" (ルビ).

  "This hiragana syllabary" would also work.
  
  While hurigana isn't necessarily wrong, furigana is how it's usually written.

• The etymology of "rubi" is just ruby, a kind of gemstones.
• The etymology of "rubi" is just ruby, a kind of gemstone.

• In British publishing industry, font sizes have given names of gemstones.
• In the British publishing industry, font sizes were named after gemstones.

• For example, Diamond is 4.5 points, Pearl is 5 points, Ruby is 5.5 points, and Emerald is 6.5 point.
• For example, Diamond is 4.5 points, Pearl is 5 points, Ruby is 5.5 points, and Emerald is 6.5 points.

• In the Meiji period, the main font size on Japanese newspapers was 10.5 points, and the font size of hiragana syllabaries was 5.2 points.
• In the Meiji period, the main font size on Japanese newspapers was 10.5 points, and the font size of hiragana syllabaries furigana was 5.2 points.

  Hiragana syllabaries could work here, but it makes more sense to use furigana.

• Since the size was similar to the size called Ruby, we have come to use the term "rubi" (ルビ) to mean the hiragana (or katakana) syllabaries.
• This sentence is perfect! No correction needed!

Nicely done! :)