Featured Chalcedony beads-thoughts?

I posted these on the finds thread. I thought someone put a 14k clasp on glass beads, but upon closer inspection, I realized they were chalcedony. Tested the spacers, coming up in the tourmaline category, guessing white tourmaline.
What do you think as to age, quality, and value? These are a bit over 20 inches long.some are more translucent blue. Some are more opaque white. I absolutely love this piece. Thanks for your help.
Lots of pics- first, in sunlight, second in compete shade outdoors.


Indoors on a pile of other jewelry for comparison.

 

I'm doubtful about tourmaline. I love the mineral for its many colors but can't recall ever seeing it in white/colorless. Had to Google to be reassured it actually exists. It must be a bit of a rarity. Unlike black tourmaline (schorl), can't quite imagine the white being used for spacers. Could it be white topaz?

 

The beads are pretty close to moonstone (which is a chalcedony), often early moonstone was a milky white colour and not the obvious blue which is more common from the early 20th century onwards. Some of those beads look chatoyant so would certainly count.

Agree with @Bronwen they are not going to be clear tourmaline, it's rare and expensive and not really suited to that shape or role. They are possibly YAG or GGG (man made clear garnet) if they are testing fairly low on the presidium meter.

 

I'd have said moonstone.

 

Beautiful, and I thought moonstone at first too, but chalcedony can be this lovely milky white.
Moonstone is a feldspar, a bit lower on the Mohs scale, so it wouldn't test as chalcedony.

Absolutely. That is why it was called moonstone in the first place. They didn't mean 'once in a blue moon'.

 

I actually have a white tourmaline ring, 10k, sold as costume. Sparkles like crazy. This hits square in the tourmaline section on the Presidium....not garnet, not white sapphire, not white topaz, not glass...this is definitely chalcedony, I have another necklace with a stone just like the better blue translucent ones.

 

Nice find, and lovely piece. I would recommend taking it to a trusted jeweler to have the stones reviewed and authenticated. Very much worth the small investment on something like this

 

I think you may be mis-interpreting the meter, the labels above the black bar (garnet, tourmaline, iolite) suggest all these gems will normally fall in the range of that black bar. How high or low in that bar depends on many factors, and any of them could be at either end of the bar, middle doesn't mean tourmaline, it could be anywhere in the range. Also these presidium meters are very unreliable so they only give a rough guide, you need other tools to make a positive diagnosis. They are pretty good at finding ruby, sapphire and for the most part topaz, but outside this I don't trust it at all as it's often wrong.

For example the size of the gem often matters, larger gems usually test higher as they have more initial thermal inertia. Quartz also tests differently depending on the axis, the same stone can give quite different results depending on the axis you test. The surface finish also affects results with better polish giving a higher result compared to a rougher finish.

 

Doh, brain glitch, of course!

Absolutely, but for some reason people seem to be associating moonstone with the strong blue tint now, which used to be the very rare examples. I blame opalite for messing up perception!

 

And people not having seen antique moonstone jewellery.

 

Yes, I know the middle reading wouldn't be the actual material...I don't think it's white tourmaline because of the lack of sparkle. My initial thoughts were quartz/rock crystal. What do you think it could be?

 

They are single cut stones,even diamonds would have very little sparkle.

 

Quartz tests higher than tourmaline.

 

Yes....it's not testing higher than the tourmaline category...so I am stumped.