INTERNATIONAL JANUARY 2011

Solitaire

78

Spotlight

s gem treatments become more advanced, harder to detect and more common place,

accurate knowledge and the skill to convey information about them become critical for creating a positive customer experience and to encourage trust.

Detection and disclosure is the key. Gem treatments are legitimate products of the gem and jewellery trade and can give your customer exactly what

Solitaire in collaboration with the Gemological Institute of America (GIA) brings you facts that every well-trained sales associate should know about the most common treatments of coloured gemstones.

they’re looking for – as long as they are fully informed about what they are buying. The challenge is to approach the discussion in a way that keeps customers interested in making a purchase.

TreaTmenTS – The BaSicSA treatment is any lab process (other than fashioning) that improves or enhances a gem’s appearance/durability. Gemstone treatments often increase a stone’s durability and visual appeal, just as the treatment of other materials

79 INTERNATIONAL JANUARY 2011

Spotlight

INTERNATIONAL JANUARY 201180

Spotlight

created or altered. The required temperatures for effectively heating a stone vary depending on the type of gemstone and the desired result. Heating is one of the oldest and most common treatments and its results are stable for many gems under normal wear.

Heating sapphire is common and, when done right, is considered an art form because it can remove secondary colours in the stone and improve its clarity. Ruby is heated with the hopes of getting rid of secondary blue, purple or brown overtones, thus enhancing the red colour. The gentle heating of amber can darken or “age” it and in some cases clarify or remove bubbles that make it cloudy.

Diffusion: This treatment involves introducing a combination of chemicals at extremely high temperatures that can alter the colour of ruby and sapphire. It may colour the stone throughout or create only a shallow layer of colour or asterism.

surface moDifications: This is the most superficial treatment because the materials don’t become part of the treated gem’s crystal structure. Its primary purpose is to deepen or induce colour. Backing, coating and painting are three basic types.

What do customers need to know before buying a treated gem? These are the main topics to cover when disclosing a treatment: why it was done; how it affects the appearance and/or durability of the stone; the treatment’s stability; special requirements regarding

improves them. Wood, for example, would splinter without oiling, and cotton clothing would all be the same colour without dyeing.

What are the common gemstone treatments in the marketplace? Bleaching: A chemical is used to lighten or remove colour; it typically dissolves and removes colouring agents. Cultured pearls are commonly bleached to remove dark spots and produce uniform colour.

cavity filling: Generally, a glass or plastic substance is used to fill and seal voids, improve appearance and/or add weight to a gemstone. Ruby and sapphire can be cavity filled.

colourless impregnation: Melted wax, plastic or other substances are used to fill pores and other openings. When they solidify, a stone’s appearance may improve, including its lustre and sometimes colour, and porous gems can become more stable. Jadeite is often bleached and then polymer-impregnated, while turquoise is often impregnated with plastic. Without this treatment, turquoise can appear porous, chalky and pale in colour, making it virtually worthless.

fracture filling (also calleD fissure filling): This treatment is similar to cavity filling, but fractures are narrow, while cavities are wide. Plastic, glass, polymer resins or oil are typically used to fill fractures that reach a gem’s surface. Emerald, ruby and diamond can be filled with high lead content glass.

heating: By exposing a gemstone to high temperatures, colour can lighten, darken, deepen or completely change, and inclusions may be eliminated,

care and durability; and whether or not it affects the stone’s value.

Certain treatments call for specific handling and care. Lattice diffusion treatment, for example, can create a colour that is shallow and some stones that have undergone this treatment should not be repolished. Fracture-filled stones often require special consideration during jewellery repairs, cleaning or even daily wear.

What’s in it for customers? Treatments can, and do, increase a stone’s beauty, value and sometimes durability. The colour and clarity of a treated stone can often be better than an untreated natural stone, making it more visually appealing. Treatments provide more affordable and abundant gem materials for your customers to choose from.

Emerald is the most common fracture-filled gem. Oils, such as cedarwood, are used to improve emerald clarity, and polymer resins help hide surface-reaching breaks and improve transparency. Fracture filling is detectable (colourless oil can be seen filling the fracture in the pictured stone) and not permanent in emerald.

Heating causes zoisite, which is typically an unspectacular brown, to become a blue, violet-blue or purplish stone more commonly known as tanzanite. Similarly, citrine is a stone that mostly begins as amethyst and is heated to achieve a “gold” colour.