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OK this is one of those far out there questions, but it is information I need. I am working on some gemstone armor rules for a pathfinder roleplaying game that I am running. To make it as accurate as possible I am attempting to derive some information from the Mohs Hardness rating of gemstones and then comparing it to traditional steel armor.

Right now I have found this information:
2.5 - Fingernail
2.5–3 - Gold, Silver
3 - Copper penny
4-4.5 - Platinum
4-5 - Iron
5.5 - Knife blade
6-7 - Glass
6.5 - Iron pyrite
7+ - Hardened steel file
10 - Diamond

So would Fullplate Steel Armour have a hardness rating of maybe 6? (Not as thick as a hardened steel file?)

If so then a +9 Fullplate made of steel with a hardness rating of 6 could possible be used to create a AC bonus for diamond armour right?

6 is what 66% of 9?

So would you use the same percentage and use it for diamond that has a hardness rating of 10?

10 would be 66% of 15?

So would Diamond Full Plate be +15 AC?

BTW I have no idea what I am doing. I don't count myself as a mathematician, but there are some pretty smart cookies on dakka, so I am hoping you all could help me out with this.

So you want realistic armor made out of gemstones?

Full Steel Plate armor is made from steel and other softer irrelevant materials.

According to Wikipedia, Steel has a hardness of 4 to 4.5

So there you go. Also note that most metals are not very "hard", but they're "tough". The ability to bend and distribute pressure is much more valuable as protective armor. Being hit in an area with a blunt object ignores how 'hard' your armor is and pushes the pressure straight into your body.

Additionally, "hardness" is not related to brittlenes. This is why glass is harder than steel. Steel bends because it's meant to bend, but it still holds strong regardless.


One of the measures that you're looking for in armor is "toughness": http://en.wikipedia.org/wiki/Toughness

A nice measure of this is "fracture toughness" (http://en.wikipedia.org/wiki/Fracture_toughness) which is the toughness of a material before it breaks regardless of bending. If you notice, steel alloy is much much tougher than glass even though glass is harder.

Diamond has a toughness 7.5-10 MPa/m^2 (http://en.wikipedia.org/wiki/Diamond#Hardness). It's noted as being worse than many engineering materials, and it is. Diamond is used well as a cutting edge because it is very resistant to deformation; you want to keep that blade sharp and precise.

Long story short, gemstone armors are an awful idea if you want to prevent damage. Just made up rules and call it "magic".

 Manchu wrote:
So you want realistic armor made out of gemstones?

Pretty much. I got a race of guys who can grow gemstones from stone like skin. I have these guys (gemsmiths) if you will, who can use elemental earth magic to shape these stones into protective armour plates like what you would find on a dragon. The armour plates can "regenerate" for a lack of a better word due to them still growing through the skin. It still takes some magic to make the shattered pieces reform, but in D&D you can explain anything with magic. All I need is some math for what this armour can do. I can explain how it is repaired and form relatively easy. I just need to math.

This is something I have seen in games before like Casltevania:

"Diamond Plate (sometimes called Diamond Armor) is an armor made of Diamond, the most endurable natural material found on Earth. It is often the strongest armor that only increases Defense, being stronger than a Platinum Plate."

 Absolutionis wrote:
Full Steel Plate armor is made from steel and other softer irrelevant materials.

According to Wikipedia, Steel has a hardness of 4 to 4.5

So there you go. Also note that most metals are not very "hard", but they're "tough". The ability to bend and distribute pressure is much more valuable as protective armor. Being hit in an area with a blunt object ignores how 'hard' your armor is and pushes the pressure straight into your body.

Additionally, "hardness" is not related to brittlenes. This is why glass is harder than steel. Steel bends because it's meant to bend, but it still holds strong regardless.


One of the measures that you're looking for in armor is "toughness": http://en.wikipedia.org/wiki/Toughness

A nice measure of this is "fracture toughness" (http://en.wikipedia.org/wiki/Fracture_toughness) which is the toughness of a material before it breaks regardless of bending. If you notice, steel alloy is much much tougher than glass even though glass is harder.

Diamond has a toughness 7.5-10 MPa/m^2 (http://en.wikipedia.org/wiki/Diamond#Hardness). It's noted as being worse than many engineering materials, and it is. Diamond is used well as a cutting edge because it is very resistant to deformation; you want to keep that blade sharp and precise.

Long story short, gemstone armors are an awful idea if you want to prevent damage. Just made up rules and call it "magic".

Very nice suggestions. I think I can take some of that and work with it. I didn't know about toughness, so if I use those numbers I can probably put something together. Something like Amber would have a very low hardness and toughness rating. I could probably make amber armour a +1 AC or +2 AC. I just want to make sure those numbers correlate to the toughness and hardness rating.

 Lord Scythican wrote:

 Manchu wrote:
So you want realistic armor made out of gemstones?

Pretty much. [...] All I need is some math for what this armour can do. I can explain how it is repaired and form relatively easy. I just need to math.

Sorry, I meant that as a rhetorical question. Absolutionis nicely sums up the point I was trying to make:

 Absolutionis wrote:
Long story short, gemstone armors are an awful idea if you want to prevent damage. Just made up rules and call it "magic".

 Manchu wrote:

 Lord Scythican wrote:

 Manchu wrote:
So you want realistic armor made out of gemstones?

Pretty much. [...] All I need is some math for what this armour can do. I can explain how it is repaired and form relatively easy. I just need to math.

Sorry, I meant that as a rhetorical question. Absolutionis nicely sums up the point I was trying to make:

 Absolutionis wrote:
Long story short, gemstone armors are an awful idea if you want to prevent damage. Just made up rules and call it "magic".

Not necessarily realistic. More like what crystal-like plates graphed to the skin that magically heal cracks and breaks. I guess the best thing to do is like you all said. Make up some rules and call it magic. The gemstones that grow from the skin can be diamond like I guess.

What I can do is say that the material grown with magic has the ability to resist breakage from forceful impact better than traditional gemstones due to a restructured macroscopic geometry and orientation that makes it tougher and more resistant to cracks and fissures. Perhaps I can say that the cleavage plane is almost not existent due to this restructuring or something to that effect? In essence I would be wiping away all the issues with some fantasy reason. Is that too BS though? It is taking the easy way out and not worth it?

I don't think phrases like "restructured macrosopic geometry" are going to make you fantasy setting any more compelling.

I mean, how do you explain a wizard casting fireball?

 Manchu wrote:
I don't think phrases like "restructured macrosopic geometry" are going to make you fantasy setting any more compelling.

I mean, how do you explain a wizard casting fireball?

Oh yeah a way more fantasy term. That was ripped from wiki!