1) Identify the material. Is it as hard as agate, or as soft as plastic? You can do this with the point of a sharp steel knife or a sharp steel pin. Steel will not mark agate. But it will scratch or dig a hole into plastic. I prefer to use a point, and to rotate the knife. This digs a tiny hole that is nearly unnoticeable.

2) The white bases of the plastic imitations are molded. There are casting indications along the length of each side, from the two-part mold. Along these lines, the pattern is slightly upset—causing little lugs or thicknesses. These can be seen in most plastic zi. (However, a careful manufacturer COULD fix these "errors" if he wanted to.). I am showing your photo with a red line drawn around where I believe the seam is (on that side of the bead), and where I can see the telltale thicknesses of the patterns—at the top and bottom of the elongated red ring.

Please test for hardness; and look for signs of molding on opposite sides of the lengths of these beads.

If you determine that the material is actually agate, these are still recent reproductions (made by Chinese manufacturers), that postdate 1993, and are most-likely less than ten (10) years old.

Viewing your new photos, I have to think the carnelian beads are also recent. These are loosely based on pema raka beads. But the melon-form grooves are too long and too mechanical-looking.

Jamey