Zirconium is 10x more expensive than brass. The weight is similar to steel, but lighter than brass. In theory, this top should not spin as long...but it's lighter weight means it is easier to spin at higher RPM...and that might just result in a longer spin.
The density of Zirconium is 6.52 g/cm3. By comparison, brass is 8.5.
This aluminum spindle is nickel plated and picks up the warm tones of the laser engraving and the Al2O3 contact point just beautifully. I don't normally make choices that put "pretty" at the top of the decision tree, but in this case I couldn't resist.
The oxide layer is incredibly durable. My introduction to working with Zirconium was making a couple of wedding rings. I was experimenting with the oxide finish and decided to remove it at one stage. I discovered the only way was to actually remove the oxide was by mechanical means, machining or major league abrasive...as in, if you want to remove the oxide you need to remove the material underneath it at the same time.
Zirconium is a "metallic" colored metal in it's raw state. The black color is developed by heating the ring to "bright orange," causing an exceedingly hard oxide layer to form. The laser is used to burn off this oxide layer, leaving a bronze/gold colored mark. Each ring is heat-treated one at a time and requires degreasing the nraw zirconium, heat treating, air cooling, and then oiling to bring out the dark blacks.
Special editions are assembled-to-order and you can choose between instrument ruby, stainless steel, Aluminum Oxide (white), or Silicon Carbide (dark gray). Aluminum Oxide and Silicon Carbide are considered "ceramic" ball bearings.
I don't think you'll see a noticeable difference in performance, but I thought some people might enjoy the difference in appearance and science behind the materials.
Instrument Ruby is a crystalline form of Aluminum Oxide and called Corundum. Corundum is a naturally occurring mineral, but instrument rubies are synthetic. This material has the distinction of being the very first gem mineral artificially created in a laboratory. A small amount of impurity (Chromium) gives ruby the distinct red color.
Stainless Steel Bearings come in a variety of grades and materials. The steel balls used in the Lambda tops are 440C Passivated Stainless Steel. This material is hardened and highly corrosion resistant. 440C is the most common material used in high-quality bearings. It's superior to chrome steel, but not the most exotic steel bearing material.
Aluminum Oxide (Al2O3) balls are classified as a "ceramic" because they are sintered from a powder base. Chemically, this is the exact same material as ruby or sapphire, but it is not a crystalline structure. Al2O3 is most commonly used as an abrasive in the manufacture of sand paper. It is also the coating that grows on aluminum when it is anodized. These ceramic balls are typically used in bearings that see extreme temperatures.
Silicon Carbide (SiC) balls are also "ceramic" and used in even more extreme bearing applications. SiC is heat tolerant up to a staggering 1800*C. It's commonly used in the manufacture of ceramic brake discs, ballistic plates in bullet proof vests, and LEDs. I recommend SiC for the extremely heavy tungsten top because it is the most durable of the three exotic contact point materials.
Durability: Contact points cannot be repaired or replaced. They are permanently press-fit into the spindle to achieve the desired degree of balance and accuracy.
The stainless bearing is the most durable option across the board. Clumsy? Steel. Got kids? Steel. Will you cry if the contact point breaks? Steel.
So why all the fuss about exotic contact points? The difference is the ruby and ceramics are MUCH harder than steel, and will spin more efficiently. It's like the difference between ice skating and snow skiing...both water...both fairly "solid" but which one is more efficient for sliding on?
A ruby is a ruby, and if you abuse it...it can chip. It's like a wine glass; works fine until you drop it. The ceramics can also shatter if subjected to enough force, but are generally tougher than the ruby. Silicon Carbide is the most durable exotic material.