Morganite Hardness and Tenacity

[onandagus1]

Help!

My girlfriend is looking at a ring with a Morganite stone--for our engagement.

She loves the ring, but I'm trying to find out how durable Morganite is.

I see that its tenacity (breakability) is rated as "brittle." But I also see that diamond is rated exactly the same. They both will fracture when hit.

In hardness, Morganite is a 7.5-8.0, so definitely more scratchable than diamond. But in looking at the hardness scale, it appears that just about anything a wedding is likely to come in contact with has a lower hardness than this. If my wife goes scratching diamonds up against her Morganite that would be a problem, but this seems unlikely to happen.

The one thing that worries me is that hardened steel also has a hardness of 7.5-8.0.

So here are my questions:

1) Any idea whether Morganite is slightly more brittle or less brittle than diamond? They're similarly brittle, but are they really the same?

2) How many of the objects we use everyday are _hardened_ steel, as opposed to regular steel? In other words, what kinds of things might scratch her stone?

Don

 

[chrono]

When looking at the overall durability, there is hardness (MOH), cleavage and toughness which are different categories.
MOH - how easily a stone is scratched
Toughness - brittleness (chips) and how easily it fractures (cleavage)

Diamond has the highest MOH of 10, so it doesn't scratch easily. It also has 4 perfect cleavage planes so if hit just right, it can split or cleave. It isn't brittle though.

Morganite is a pink beryl with MOH of 7.5 and indistinct cleavage. Its only drawback is its brittleness, which means it can chip at facet junctions and the girdle. It isn't a good candidate for an everyday ring stone but with care, can make an e-ring stone. If removed once at home, not worn to the gym and such, it could last a few years without obvious wear and tear.

In short, a diamond is far more durable than morganite. It is less brittle than morganite. Hitting the ring against the wall, door, kitchen counter is sufficient to chip a morganite.

 

[onandagus1]

OK. Thanks a ton!

Don