How jewelry is made using the lost-wax casting method (and what cast-in-place is)

There are jewels that are manufactured and jewels that are crafted. The lost-wax casting technique belongs to the latter category: it is a handcrafted process where a piece is first created as a sculpture (in wax) and then transformed into metal through melting.

At Soleilu we work with traditional processes because they allow something rare today: real textures , character , and pieces that don't look "factory perfect".

What is lost wax casting (explained without technical jargon)

Lost-wax casting is a casting technique that has been used for thousands of years. The idea is simple:

1. The wax model is created.
   First, the jewel is sculpted in wax (by hand or from a wax/resin impression). That model is the "original jewel," but in a material that melts.
2. It is placed on a cast iron "tree".
   A channel (sprue) is added through which the molten metal will later enter. Several pieces can be joined to the same shaft.
   
   Photo taken from Asen Asumani 's website
3. It is coated with a refractory material
   Everything is placed in a cylinder and covered with a special (refractory) plaster that withstands high temperatures. It is then left to set. Image taken from the website of Reguera, a foundry in Barcelona.
   
4. The wax burns: that's where the "loss" lies
   The cylinder is heated in an oven. The wax melts and evaporates, leaving a hollow precisely shaped like the jewel.
5. The metal is melted and the mold is filled.
   Silver or gold is poured (or injected with centrifuge/vacuum) into the cavity left by the wax.
6. The mold is broken and the rough piece appears.
   The refractory brick is broken (it's not reused), the piece of wood is cut, and then begins the part that many people don't imagine…
   
   Image taken from the website of Fundesti, an artistic foundry in Tarragona.
   
7. Cleaning, filing, sanding, polishing and finishing
   This is where the workshop earns its keep: removing marks, refining edges, adjusting sizes, polishing, texturizing, patinating, engraving… and finally mounting the stone if it wasn't fused with it.

In short: lost-wax casting transforms a sculpture into metal. That's why each piece of jewelry can have a "soul," even within the same design.

What is cast-in-place?

Cast-in-place (casting “with the stone in place”) is when the stone is placed in the wax pattern before casting, and during casting the metal solidifies around it, leaving it already “mounted”.

Simply put: instead of melting the jewel and then setting the stone, the stone enters the process earlier, and is trapped in the metal as it is born.

Why it's done (and why it's not always done)

Advantages

• It can create organic and highly integrated effects: the stone appears to be "born" within the piece.
• It allows for designs that are difficult to achieve with traditional settings.
• It adds a more "magical" and artisanal character to the final result.

Real limitations (the ones almost no one talks about)

• Not all stones can withstand the process. Melting involves extreme heat and sudden changes; many gems are damaged, crack, lose color, or explode (literally).
• The result can be more unpredictable. Sometimes a stone comes out perfect; other times, it doesn't.
• It requires very careful selection of the stone, its size, its shape, and the design of the wax "nest".

Internal cracks: “defect” or beauty

In some gemstones, especially when working with demanding processes like cast-in-place , internal microcracks or subtle changes within the stone can appear. And here's where it clashes with "industrial" jewelry: some designers specifically seek out these imperfections, because they make each gemstone unique.

At Soleilu, if a gemstone cracks internally but remains stable and secure in its setting, we don't try to "fix" it or hide it . We leave it as is.

These internal cracks aren't just an "ugly" break: they often form their own universe , with patterns that resemble galaxies, fractal ice, or lines of light. The result is a stone with personality, telling the true story of its creation and making your piece of jewelry even more unique.

Cairo Beige

Honest note: if the crack compromised the gem's strength or its setting, that stone wouldn't be used in a final piece. The priority is always that the jewelry lasts for generations and is comfortable.

Which stones tend to work best

In general, the stones that best tolerate workshop processes (depending on cut, quality, and conditions) are some synthetic stones, such as certain cubic zirconias, and materials specifically designed for jewelry. In contrast, many natural stones (especially those with inclusions, porosity, or treatments) are more delicate.

Important note: even within the same stone "family," performance can vary. Cast-in-place castings do not offer 100% guarantees.

Why this process matters when choosing jewelry

Because it defines how a piece feels:

• Texture is not a filter: it's physics.
• Micro-imperfections are not "fails": they are a trace of the process.
• Two similar pieces may not be identical, because a workshop is not a photocopier.

Frequently Asked Questions

What is the lost wax technique in jewelry?
It is a casting process where the piece is first created in wax, then that wax is removed with heat and the resulting cavity is filled with molten silver or gold.

Is lost wax casting a handcrafted or industrial method?
It can be used in both contexts, but the result changes a lot: when there is real manual work (model, textures, finishes and polishing), each piece retains character and small variations.

What does cast-in-place mean?
It is a variant of lost wax in which the stone is placed in the wax model before melting, and the metal solidifies around it, leaving the gem integrated into the piece.

Are all stones suitable for cast-in-place?
No. Many gemstones cannot withstand heat or sudden changes and can crack, fade, or become damaged. That's why it's essential to choose suitable materials and precisely design the wax setting.

If a stone cracks on the inside, does that mean it's broken?
Not necessarily. If the stone remains stable and secure in its setting, those internal microcracks may just be a visual effect and form unique patterns.

Why are internal cracks sometimes left in Soleilu?
Because they can create a unique “universe” within the gem: lines, reflections and patterns that make the piece even more unique, as long as it does not compromise its strength or safety.

What is the difference between lost wax and traditional setting?
Lost-wax casting is the method used to create the jewelry in metal. Traditional setting occurs afterward: the piece is melted and then the stone is mounted. In cast-in-place casting, the stone is inserted first and becomes integrated during the casting process.

Are jewels made using the lost-wax casting method identical to each other?
They may be very similar if they start from the same model, but it is normal for there to be subtle variations in texture and finish: it is part of the handcrafted nature of the product.

Does lost wax casting affect the durability of the jewelry?
Durability depends primarily on design, thickness, finish, and use. A well-made lost-wax casting can last for generations.

How do you care for a silver jewel to keep it beautiful?
Store it dry, avoid perfumes and harsh products on the piece, and clean it with a soft polishing cloth when needed. For pieces with stones, avoid impacts and sudden temperature changes.