Can you make titanium or tungsten rings?
There is a reason why there aren’t many available ring stiles in titanium or tungsten. This has something to do with melting temperatures of these metals, the chemical composition of the mold and also the properties of the metals. Many customers want an extra strong ring and immediately think of tungsten, then figure it should be cheaper than gold. It seems like a perfect solution. Not at all! Silver and gold have relatively low melting points. Pure silver melts at 963 C, while for pure gold it is 1064 C. Most jewelers use electric melting furnaces. The heating element in the furnace is made out of steel (probably alloyed with other metals for durability). It melts at 1510 C. After a while, the heating element needs to be replaced. Tungsten melting point is 3442 C, more than double the melting point of the heating element! In other words one cannot melt tungsten in an electric furnace, even if the heating element was made out of pure tungsten! O.K. why aren’t then people make heating elements that can sustain that temperature? They can’t. Tungsten is a metal with the highest melting point! There is only one element with higher melting point than tungsten. Believe it or not, it is carbon. Carbon burns when there is enough oxygen, but if pure carbon is just heated with no flame it would not start burning. It melts at 3550 C, not that much higher than tungsten. For that reason, crucibles (the vessels that hold molten metal) are made out of graphite. As you can see, just melting tungsten is a serious problem, then holding that molten metal in something that can sustain its temperature is another, and the third problem is pouring it into a mold. Obviously tungsten can be melted only with flame.
Standard mold material for jewelry casting is gypsum (calcium sulfate) and microscopic silica. The material is very similar to Plaster of Paris, just has higher silica content. It is one of the most carcinogenic materials to humans. It is almost as bad as asbestos. Microscopic silica gets deep into the lungs and the immune system starts attacking it as if it was a pathogen, but it is not. So basically our own immune system creates carcinogenic peroxides to fight silica (completely unaffected) and then cause damage to the lungs and frequently cancer over longer periods of time.
The temperature at which calcium sulfate will start decomposing is about 1300 C which means that even casting steel is going to cause problems as steel melts at 1510 C. When molten metal rushes in the holes of the mold, only gold will be unaffected, but every other metal will have something sort of oxidation on the surface. The higher the temperature, the more oxidation and possibly enough decomposition to cause uneven surface. If one tried to pour molten tungsten into this kind of a mold, it just wouldn’t work. The only solution is pure silica mold. This thing was discovered during WWII. When colloidal silica (colloidal sand) dries it forms a relatively strong shell that can be formed around an object in layers. This method is called “ceramic shell” and it is used for casting sculptures. Silica melts at 1713 C which is still not even close to tungsten so the end result of this casting is pretty rough cast. It can’t be as fine as required for jewelery. There are only a handful companies that can cast tungsten. They produce rough casts tubes that are filed with diamond tools and only then jewelers slice them with again diamond tools and make simple wedding bands. An engagement rings with prongs just can’t be made in tungsten. The fourth problem with tungsten would be setting stone. Prongs need to be made out of “soft metal” such as silver or gold, so once a prong is hit it would fold over the stone. In case of tungsten if one hits the prong one of these three things will happen:
b) the prong would break if it is small enough
c) the prong will damage the tool
As you can see, making tungsten rings is neither cheap nor easy. It may sound cool but it is like saying: it would be cool to have an anti-gravity machine. Eventually the technology would catch up and some solutions may be available in the future but it seems that we are not there yet.
How about titanium?
Everything said about tungsten applies to titanium, just to the lesser extent. Since titanium melts at 1668 C it is still manageable to work with, although not as easy as silver or gold. The fourth problem associated with setting stones in prongs still remains.
I want something stronger than silver, what is the solution?
I work with a proprietary alloy called Acero Forte. It is almost as strong as steel but melts at lower temperatures. A ring made out of this material can scratch a quarter easily. For now it seems the best solution for making strong rings. Being a non-precious metal alloy people with metal sensitivity should avoid it. Plating it with gold or silver may help, but my suggestion is using the standard metals for jewelry. One really needs an extra strong ring.
Here are some melting point of the materials mentioned in the text:
Silver 962 C
Gold 1064 C
Steel 1510 C
Titanium 1668 C
Silica 1713 C
Tungsten 3442 C
Carbon 3550 C
Temperature on the surface of the Sun 5505 C