moissanite and… toughness?

posted 4 years ago in Rings
Post # 3
847 posts
Busy bee



As far as Hardness goes, I think it’s well known on the board that Moissy is on the Moh’s scale at 9.25 — which means it can only be damaged or ‘flaked’ off by things harder than it. Glass is a 5.5 and a steel file is a 6.5. While these seem really close to each other, an 9 is twice as hard as an 8. A 10 is four times as hard as a 9.

Regarding toughness: Moissanite’s atomic structre does not have a direction of cleavage like diamond does. Diamond, while extremely hard can chip or shatter when struck by a hard object on its cleavage plane. Moissy isn’t indistructable by any means, but can take more damage in that regard.

I’m sure bees who have had their Moissy for years can chime in.



Post # 4
727 posts
Busy bee
  • Wedding: May 2014

@MsSunshineBee:  I just read the other day that someone’s moissanite shattered when they dropped their ring.


Post # 6
888 posts
Busy bee
  • Wedding: June 2014

They can flake off. We have had three flake apart. It is a synthetically made stone. Yes it exists in nature but is rare and mostly green and not clear. I have experience with the stone and in my opinion is much more destructable than diamond. A 9.25 is still worlds away from a 10. Think of it as having a hardness of a ruby or sapphire, it is absolutely possible. I am also not a fan of either diamonds or moissanite. I do wear a diamond but secretly wished for aquamarine.

Post # 7
118 posts
Blushing bee
  • Wedding: August 2000

I recently read about how silica sand is mixed with carbon at extremely high temperatures to create the crystal.  I believe it is then “grown”?  It was interesting because it reminded me of tungsten carbide, which is tungsten powder mixed with carbon.  We have tungsten carbide rings, so I remember researching how they can shatter or chip, and remember reading not to leave them in an ultrasonic cleaner for an extended time (loses cohesion??).  I wondered if it’s kind of the same principle?  I have moissanite, and it continues to fascinate me.  I’d love to be steered in the right direction about this!

Post # 9
1518 posts
Bumble bee
  • Wedding: July 2012

SiC (moissanite) is one of the most atomically stable crystal structures we know of. It is only about 30% as hard as a diamond, but the indistinct cleavage planes along with stronger atomic bonding make it an inherently tougher material. That isn’t to say there are not cases where there could be an unseen flaw in a stone that causes fracturing if hit right, but that’s a very rare scenario.

Now, currently the stones produced by C&C all have these ridiculously thin girdles (where the pavilion meets the crown) which means that the girdles are more prone to chipping than a stone cut with a medium/thick girdle. This is not an inherent problem with SiC, but a created one due to the cut.

I’ve been reading up on and researching SiC for years, and this is the first time I’ve EVER heard of anyone claiming “flaking” of the stone, which is nonsense.

Post # 10
4 posts
  • Wedding: March 2016

May I weigh in on this old thread?  Sorry to resurrect it, but this was the ONLY mention I could find online about this matter. I have 40+ Moissanites in my ring. It is a remake of my original because my original was cheaply made and the stones started falling within two months. Now my remake is also loosing stones because a few are fractured (me vs filing cabinet, cabinet won). I’ve noticed the ones that are fractured do flake if I scratch it with my nail (bad bad bad me). When I got my hand caught on the  cabinet, one stone lost quite a chunk and when I poked it because I noticed it was definately less fiery than the others it “flaked”. I put that in quotes because all my Moissanites except the center stone are lil mellies and perhaps the appearance of flaking is due to their tiny size. My jeweler is NOT happy and is hard pressing me to replace my small moissanites with diamonds (for $1300 after I already had it custom made this summer). *sigh*. I came to the Internet searching for answers to my dilemma . I can tell there is one more bound to fall out it has taken a whitish appearance the other one had before it flaked into pieces. I just don’t know if that. 5 moh hardness is going to make a difference. I mean we are talking about a sudden force, even diamonds would fracture under that pressure I assume. 

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