Aquamarine vs Blue Topaz vs Blue Zircon: A Curator's Guide

Three gems can all wear a beautiful blue — and they could hardly be more different underneath. One is a precious, durable classic; one is an abundant, vivid, treatment-born favourite; one is a brilliant natural mineral that is constantly confused with a synthetic it has nothing to do with. Knowing which is which is the difference between an informed purchase and a surprised one.

In one line: aquamarine is the precious, value-holding natural blue beryl; blue topaz is the affordable, vivid blue that owes its colour to treatment; blue zircon is a fiery natural mineral (and not cubic zirconia).

At a glance

Aquamarine — the precious blue

Aquamarine is the blue variety of beryl (emerald's cousin), coloured by iron, and it is the only one of the three that the trade regards as a precious coloured stone. Its pastel sky-blue is frequently refined by gentle heat that resolves a greenish cast into pure blue — a standard, stable, disclosed step — and the deepest material (the "Santa Maria" blue) commands real premiums. Durable, classic and value-retaining, aquamarine is the one of the three you buy to keep.

"This is Cambodian blue zircon. Most blue zircon that we're seeing today is coming from Cambodia — a natural mineral, and nothing to do with cubic zirconia." — David Saad, Skyjems

Blue topaz — vivid, abundant, treatment-born

Here is the honest truth that surprises many buyers: nearly all blue topaz begins as colourless topaz and is given its blue by irradiation followed by heat. The result — sky, Swiss and London blue — is vivid, stable, and inexpensive, which is exactly its appeal: a big, bright blue for a modest price. There is nothing wrong with that, provided you know it. Just don't expect blue topaz to hold value like aquamarine; it is abundant by design. (It is durable but has a cleavage direction, so set and wear it with reasonable care.)

Blue zircon — the fiery natural mineral (not "CZ")

First, the essential clarification: zircon is a natural mineral, and it is not cubic zirconia. Cubic zirconia (CZ) is a man-made diamond simulant with a confusingly similar name and no relation. Natural blue zircon — typically heat-treated from brown rough — has a high refractive index and strong dispersion, giving it a brilliance and "fire" that can outshine the other two. It also shows noticeable facet-doubling (a charming tell) and its facet edges are a little more delicate, so it rewards a protective setting. For sheer liveliness in a blue, zircon is the connoisseur's surprise.

Value and which to choose

• Aquamarine if you want a precious, durable, value-holding natural blue — the heirloom choice.
• Blue topaz if you want a big, vivid blue for a modest budget and don't mind that the colour is treatment-born.
• Blue zircon if you want a brilliant, fiery natural blue with character — and now you know it is nothing to do with CZ.

We carry all three, with treatments disclosed. Inquire with the Curator or browse the aquamarine, topaz and zircon collections. Toronto: 416-366-3335.

Frequently asked questions

Is aquamarine more valuable than blue topaz? Generally yes. Aquamarine is a precious natural beryl that holds value, while most blue topaz is abundant colourless topaz given its colour by irradiation and heat, making it inexpensive. They serve different purposes and budgets.

Is blue topaz natural? The topaz is natural, but its blue almost always is not — nearly all blue topaz is irradiated and heated from colourless material. The treatment is stable and disclosed; natural blue topaz is rare and usually pale.

Is blue zircon the same as cubic zirconia? No — and this is the key point. Blue zircon is a natural mineral; cubic zirconia (CZ) is a man-made diamond simulant. The names sound alike but they are entirely unrelated.

Is blue zircon a good gemstone? Yes — natural blue zircon has exceptional brilliance and fire and a distinctive character. It is a little more delicate at the facet edges, so a protective setting is wise.

Which blue holds its value best? Aquamarine, of the three — it is the precious, value-retaining choice. Blue topaz is inexpensive by nature; blue zircon sits in the mid-market on its natural-mineral character and brilliance.