Two pieces of jade joined as one are called a jue.
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珏 is literally two jade glyphs set side by side, so it means a matched pair of jade. Because jade is prized and the shape is balanced, it is a popular character in personal names.
The left side is the jade radical, the side form of 玉 written without its dot. Identical in shape to 王 (king), but in jade-family characters it is the jade glyph - one of the two jade pieces in 珏.
The right side is the full 玉 (jade), keeping its dot. Two jade glyphs together form a meaning-compound: a joined pair of jade pieces, which is exactly what 珏 denotes.
