Once a jewelry design is finished in CAD and printed as a castable wax or resin pattern, the next big decision is metal. Choosing the right jewelry casting metal affects price, durability, color, and how the finished piece will wear over decades, not just how it looks the day it leaves our studio. At eCadCam in Los Angeles, we cast custom rings, pendants, and other fine jewelry from CAD models every week, and clients almost always have questions about gold, silver, and platinum before we send a piece to casting. Here is a practical breakdown to help you choose.
Gold: Karat, Color, and Alloy Basics
Pure gold (24K) is soft and impractical for everyday jewelry, so cast pieces are almost always an alloy. 18K gold is 75% pure gold mixed with metals like copper, silver, or palladium; 14K is 58.3% gold. Higher karat gold has a richer color and better resistance to tarnish, but it is softer and more prone to scratching, which matters for a ring worn daily. Lower karat gold is more durable and generally less expensive, which is why 14K is the most common choice for engagement rings and other pieces meant for daily wear.
Color comes from the alloy mix, not from a coating on standard gold. Yellow gold uses copper and silver in the mix; white gold adds palladium or nickel and is typically finished with rhodium plating for a bright white look (plating that wears over time and can be reapplied); rose gold uses a higher proportion of copper for its pink tone. All three can be cast from the same CAD model and wax pattern, so choosing a color is a decision you can make late in the process without redesigning the piece.
Silver and Platinum: Where Each One Fits
Sterling silver (92.5% pure silver, alloyed with copper) is the most affordable casting metal and is a good choice for fashion jewelry, samples, and pieces that will not see decades of daily wear. It tarnishes faster than gold or platinum and is softer, so fine prongs and thin details can wear down sooner on pieces worn constantly.
Platinum sits at the other end of the spectrum. It is denser and heavier than gold, naturally white (no rhodium plating needed), hypoallergenic, and highly resistant to tarnish, which makes it a popular choice for engagement rings and heirloom pieces meant to be passed down. Platinum is also more expensive per gram and, because it is denser, a platinum piece uses more metal by weight than the same design in gold, which compounds the cost difference. It is also a harder metal to cast well; not every casting house runs it, but it is a routine option for us when a client wants that specific look and longevity.
How Metal Choice Affects Your CAD Model and Casting
- Prong and wall thickness. Softer metals like silver or high-karat gold need slightly heavier prongs and shanks to hold up over time; we adjust minimum wall thickness in the jewelry CAD model based on the metal you choose.
- Shrinkage. Different metals shrink by different amounts as they cool from molten to solid in the mold, so the wax or resin pattern is scaled to compensate. This is calculated per metal, not applied as a single universal number.
- Stone setting. If a design includes gemstones, the setting style (prong, bezel, pavé, or channel) needs to work with the strength of the chosen metal. Softer metals may call for more support around delicate settings.
- Cost estimating. Metal price fluctuates with commodity markets and is typically billed by weight, so the same CAD design can vary noticeably in price depending on metal and karat.
Because these factors are baked into the model before casting, it is worth deciding on metal, or at least narrowing it to a couple of options, before your jewelry CAD file is finalized. If you are undecided, we can print a resin or wax pattern first so you can confirm fit and proportions before committing to a specific metal.
Get Your Jewelry Design Cast the Right Way
Whether you are designing a single custom ring or setting up small-batch production for a jewelry line, choosing the right casting metal is one of the most important decisions in the process. Our Glendale studio handles jewelry CAD, wax and resin 3D printing, and lost-wax casting in gold, silver, and platinum, all under one roof, backed by 22+ years of CAD and fabrication experience. Request a jewelry design quote, call us at 213.489.1173, or visit us at 4212 San Fernando Rd, Glendale, CA 91204.