jewel, peculiar (treasure), proper good, special

Boyd’s Bible Dictionary:

(joy). Ornament (Gen. 24:22; Num. 31:50).

“Jewels” From Concise Bible Dictionary:

A general name for costly ornaments of dress, of silver, gold, or precious stones (Ex. 3:22; Song of Sol. 7:1; Isa. 3:21; Hos. 2:13, and others). In Genesis 24:53 the word is used for the equipment of the bride. In Malachi 3:17 it is used symbolically for the remnant that will be precious to the Lord of hosts in a future day, as the saints are now during the rejection of the Lord Jesus by the world.

“Peculiar People, or Treasure” From Concise Bible Dictionary:

Except in Ecclesiastes 2:8, where “the peculiar treasure of kings” is gathered by Solomon, these expressions both in the Old Testament and in the New Testament refer to what God’s people are to Him (Ex. 19:5; Deut. 14:2; Deut. 26:18; Psa. 135:4; Titus 2:14). The terms imply a possession upon which a specially choice value is set. 1 Peter 2:9 is a little different: “Ye are a people for a possession.” (compare Mal. 3:17.)

Strong’s Dictionary of Hebrew Words:

Transliteration:
cgullah
Phonic:
seg-ool-law’
Meaning:
feminine passive participle of an unused root meaning to shut up; wealth (as closely shut up)
KJV Usage:
jewel, peculiar (treasure), proper good, special