Hello Stefany,

I know these beads from a Thai context.

The literature on ancient beads tells us that joined agate beads were made in antiquity. Either these were made to imitate banded agate beads, or to imitate chemically-decorated stone beads.

The current Thai beads likewise imitate a class of Thai decorated agate beads (that are sometimes compared to zi beads). I have inquired of the (two) experts I know as to whether they believe there are modern interpretations of such beads (with no opinions offered).

About three years ago and over several months, I bought specimens of the recent joined beads, from eBay offerings (where they were misrepresented as "ancient"). I got enough to make a necklace. I bought two additional beads that are so long they do not easily fit into the design. My photos of these beads are stored on an external drive, and so are not at-hand.

I believe the stones are reddish carnelian and black agate. I think the pieces are glued together as flush surfaces, but one piece has a carved recess on the ends (creating a thin trench)—and this is filled with a hard white compound, to simulate the decorated white lines of the original beads. This also disguises the joins. However (as you probably discovered), it's possible to feel these joins by passing you fingernail lightly along the length of the beads.

I'll try to shoot a new photo, since this will be easier than looking for photos from ca. three years ago.

Jamey

P.S.—I had intended to come to London in June. But, alas, you know what happened. And I have been sheltering at home since March. I resent not being able to get out and see anyone; but I am resigned....

Jamey - good i'm confident it is Thai- yes layered opaque black, white and somewhat translucent cornelian .. but the joins are incredibly solid and exact... its hard to know when the adhesive technology became available and it certainly appears to have been drilled in one piece after glueing...
if mine were historically old i imagine that it would not be round in cross-section but flatter.

I would say you bead and my two very long beads may be the most-recent of these reproduction beads.

as i'm stingy and not too interested in collecting anything if its expensive but happy to have an attractive example of a type-
what adhesive or cement do you reckon is used with these laminated layers? it must be almost as strong as the agate and jasper..

This is the necklace I constructed, with the joined agate beads I acquired two years ago. Full view and closer detail. They are combined with other plain beads (from eBay), as well as Thai silver beads that I have had for a number of years.

Here, I'm showing the central bow-shaped bead, and the two most-recent beads I bought—that resemble your bead in details (that differ from the "earlier" beads with which I am familiar).

I am confident you will see their similarity.

Hugs. Jamey

I'm going to guess they used a 2-part epoxy to glue the sections. Epoxy is used a lot to glue stones.
Examples:https://www.stonetooling.com/Adhesives-s/249.htm

Epoxy is a good and easy guess—since it is so commonly used, and is probably available even in Thailand.

I know several people who routinely use it to join like and unlike parts together.

I do not. My results with two-part Epoxy have been uniformly poor. It's either too hard and brittle, or it doesn't harden and remains gummy. I don't have the knack.

I'd rather use Super glue. Though it's not 100% either....

JDA.

Museum conservators use high quality non-yellowing hxtal. They clean the parts scrupulously , measure the proportions exactly and mix on a clean glass plate with a glass rod. After adjusting the epoxied piece to stop any potential creep you need to let it sit for a week undisturbed to reach full strength. Fresh normally available epoxies can work well with the same precautions but it is not simple to get the proper mix ratio. Some will brush on a bit of the hardener to the joint later to assure enough hardener was applied.

I worked with high-end epoxy products for aerospace applications for over 30 years. The key to long-lasting joints is to carefully prepare the surface by sanding or sand-blasting, then degrease with a solvent like acetone, if possible apply and cure a compatible primer, then apply the epoxy adhesive. Some pressure is needed to create a thin, uniform bond line and squeeze out air pockets, if possible.
When bonding stone, you could also heat the part to advance the cure - even low temperatures would help.
Many of the original epoxies were very brittle, but now most have toughening agents added. I researched this a bit when I needed a reliable, room temperature cure epoxy and I recommend Gorilla clear 5 minute epoxy. As indicated in Frank's post, museums have epoxies that won;t yellow with age(very common).
You need to take some care to measure out the quantities of the two components correctly but if the material hasn't "gone bad" with age, the ratio of the two parts can be off somewhat and you can still get a good cure.
If I needed to make beads like the ones shown - I would bond together stone layers as a big sandwich in a press to get thin bond lines, using some heat and a top end epoxy. After the cure I'd slice the block into blanks and proceed with shaping into beads. In my industry we used saws with gang blades to slice out a bunch of pieces with one pass. A production line could be set up to fabricate these types of beads very quickly and theoretically could be mostly automated.

I suppose that composing layered blocks is exactly what the beadmakers did, to create the beads shown. (Particularly the two longer more-recent beads, and Stefany's bead.)

Nevertheless, I would also assume that the manufacturer is a small industry, that is hand-work-driven, and small in output. These beads remain fairly rare.

Nevertheless, given the desire and the motivation—and cash support—an industry could be developed exactly as you suggest. And these beads could be cranked-out.

JDA.

P.S.—The artisans I know who work with Epoxy, and have good results, do not take any of the precautions/preparations mentioned here and above. They are more along the lines of mix/glue/wait. And they are happy with their results. As I said, I just don't have the knack for doing that successfully. So I don't do it.

I use epoxy all the time for adhering gemstones to brass dops. They get rather heavy use, including water, while cutting. I almost never lose a stone, when I do things correctly.
If you have trouble getting the correct proportions, what works is to use, say, a piece of wax paper, set it on a gram scale. Apply the epoxy you want and note the weight. Apply the same amount of hardener to achieve the correct doubled amount.
Lately I've obtained some Paleo glue. It comes for various uses--some thin and some thick. They use the thin on very porous fossilized bone. I haven't tried it yet on stone joins. Comes with a fluid for breaking joins.