Jewelry, Gems, & Minerals/Turquoise Fracture/crack
Hi, I'm not sure if my vintage Turquoise ring received a whack on a hard surface, or it happened while this unusual shaped stone was being set. ( I was aware this was there, but it seemed ok ).
But I have a really nice ring, beautiful stone (turquoise), & there is a visible triangular area that first looked like matrix and being the type of cut this stone has the surface has a slight bumpy feel yet still smooth surface. Last night I got it out due to someone's interest in it.
As I was looking at it, I ran my finger across the top when the ring I am wearing accidentally/lightly tapped the stone and I heard a somewhat hollow sound. I got the work lamp out and really examined it, and yes I felt a barely fine line along the lines we thought was matrix. The area in question has a rather triangular shape( it's a large stone ).I'm guessing this fine line goes deeper after hearing the sound that tap created. I do not wish to reset with another stone, but is there something I can do to stabilize it ? The remainder of the stone has no defects, the setting is secure, no loose areas. I feel I should not sell it as is, but told them I would let them know what I could find out. Your help will be greatly appreciated....Thank you for your time.. Sincerely, rose
While much turquoise sold within the last 20 years is treated by adding dyes and plastics to the stone, old vintage stones are generally natural and will respond fairly well to crack sealing with a good epoxy cement. The cure is not every perfect but will stabilize the stone and hold all together. Breaks along matrix pattern lines are not uncommon, all depending on the strength of the stone in the first place.
The epoxy cement must be of the sort that when cured is water clear, not the typical amber color. The cement must also somehow penetrate at least to a partial degree into the crack and excess wiped away so the fix is not so visible.
First, you need the cement. My recommendation is Hughes Epoxy 330, a 2 hour cure time two part epoxy. Do not use the 5 minute quick cure epoxy cements because there is simply not enough time to do the job with those. If you can find another brand that is clear and colorless when cured that should do as well. Be sure it has at least a 2 hour cure time once the two parts are mixed.
Next, the gemstone must be clean of oils and any “stuff” which would prevent a good joining of the crack edges and allow a good contact with the surfaces by the epoxy cement. Soak the stone in alcohol (rubbing alcohol should be ok) for about 5 minutes and rinse it with water. Dip in the alcohol once more and remove, wipe off and allow to air dry. This is to remove skin oils and residue which might get in the way of a good glue joint.
How to get the cement into the cracks? This is the trick and secret of the entire process. When two part epoxy is gently heated it becomes very liquid and runny. Soon afterwards, the heat makes the cement begin to cure and harden. That last part is why you need a slower curing cement. Heating must be gentle and hot too hot to touch by any means. You do not want to heat damage the stone. A normal light bulb gets hot and that is just enough to heat the jewelry along with the stone. A gooseneck desk lamp is good because the bulb may be brought down close to the item and all will warm up gently for about 15 to 20 minutes. Touch the jewelry (not the stone) to determine how hot it is. Just starting to be on the hot side of overly warm is what you want. You may have to rig some way to gently heat the piece.
When the jewelry and stone is warmed up, mix the cement according to directions. This is generally equal parts. Use a plastic surface or other non-absorbent surface and use a tooth pick of similar tool to stir the cement. With the warmed jewelry taken from the heat, immediately put a little cement on the crack and used the tool to run the cement around the crack. With the stone warm, the cement will take on a more watery consistency. (Put the toothpick back on the edge of the unused cement. This will be your test device to see when the glue is hard without disturbing the stone.) Set down your jewelry and allow the ring to cool. The heat then cooling allows the cement to go into the cracks and not simply stay on the surface. After about 5 minutes, wipe off excess cement with a totally lint free cloth or paper. (Lint will stick and get into the crack!) After about 10 minutes, take the lint free cloth and with a dab of the alcohol go over the crack again, not rubbing on the crack too much but with the idea of removing any excess cement. Once cured, the cement will be almost impossible to remove so do it now. You can always try adding a bit more cement later after the first is cured and hard but this is generally not needed.
When all is cured as you can tell by trying to move the toothpick in the leftover cement, the job is finished. See if any more cement is needed but always keep in mind it is not more cement on the stone that counts but what went into the cracks and was able to join well because the stone was cleaned well to start with.
Rose, this should do the trick. You will need to work out how to gently warm the stone without using direct heat. You might even use a hair drier on low heat is there is no other option. Just be sure to use a gently and easy heating up. It is sudden strong heat that will damage a gemstone.
If you have any questions, feel free to get back with me with a follow-up. Best wishes with the fix!
God Bless and Peace. Thomas.