The Ultimate Guide to Sourcing Gemstones
The right gemstone is rarely the first one you see. It's the one whose colour, durability, treatment history and price all fit the person who'll wear it.
Our founder, Mr Cheshire, started in the trade in 1982, working for a gemstone dealer in London's Hatton Garden. In 1988 he began making diamond and gemstone jewellery for the UK trade. He has travelled to Bangkok for more than 40 years, building close relationships with some of the world's finest gem dealers, and also buys at international exhibitions such as Hong Kong. His son Sebastian joined the business in 2019. Sebastian studied gemmology at the GIA in London and has worked in a diamond sorting office in Mumbai.
This guide covers how to choose any fine gemstone, with extra detail on rubies, sapphires and emeralds, our three core stones. It's what we tell customers in our Solihull, Chester and Birmingham stores: what matters, what to be wary of, and how we find a specific stone when nothing in the window is quite right.
What to look for in a coloured gemstone
With coloured stones, colour comes first. A slightly included stone with outstanding colour will usually be worth more than a flawless one with dull colour. That's the opposite of how many people think about diamonds.
Colour
Judge three things: hue (the colour itself), tone (how light or dark it is) and saturation (how vivid it is). The most valuable stones sit in the middle of the tone range. Too dark and a sapphire looks inky in normal light; too light and it looks washed out.
Look at a stone in daylight, under shop lighting and under a warm indoor bulb. Some sapphires and rubies change noticeably between them. Ask to see it on a white surface and in your hand, not only on a black velvet pad.
Clarity
Most natural coloured stones have inclusions, and some are expected. In emeralds, inclusions are so normal that the trade calls them jardin, French for garden. What matters is whether an inclusion breaks the surface, sits near an edge or prong, or clouds the colour. A fracture in the wrong place can make a stone fragile.
Cut
Coloured stones are usually cut to save weight rather than to maximise sparkle. Tilt the stone and look for a "window": a dull, see-through patch in the middle where light leaks out. A well-cut stone stays lively across its whole face.
Carat weight and size
Carat measures weight, not size. Rubies and sapphires are denser than emeralds, so a 1 ct ruby looks smaller than a 1 ct emerald. Ask for the millimetre measurements as well as the weight. Prices also jump at round numbers, so a 0.95 ct stone can be noticeably better value than a 1.00 ct one.
Treatments
Treatment is normal, but it must be disclosed. Here's how we see the common ones:
- Heating rubies and sapphires: standard practice, stable and permanent. Untreated stones of similar quality command a premium.
- Oiling or resin-filling emeralds: very common. Minor oiling is widely accepted; heavy filling lowers value and needs more care over time.
- Lead-glass-filled rubies: these are composite stones, often more glass than ruby. They can be damaged by everyday chemicals and jewellers' heat. At Cheshires, we don’t sell lead-glass-filled rubies.
- Beryllium-diffused sapphires: the colour is created by the treatment rather than improved by it. These should be priced well below heated stones.
If a seller can't tell you how a stone has been treated, that's a reason to pause.
Will it stand up to everyday wear?
For a ring worn every day, durability matters as much as beauty. Rubies and sapphires are among the toughest gems after diamond. Emeralds are beautiful but more vulnerable, and that should shape both the setting and how they're worn.
| Gemstone | Hardness (Mohs) | Everyday ring? | Our advice |
|---|---|---|---|
| Sapphire | 9 | Yes | Excellent for engagement rings and pieces worn daily. |
| Ruby | 9 | Yes | As tough as sapphire, provided it isn't glass-filled. |
| Emerald | 7.5–8 | With care | Choose a protective setting, such as a bezel or rub-over, and take it off for housework, the gym and gardening. |
Hardness is only part of the picture. An emerald with surface-reaching fractures can chip from a knock that a sapphire would shrug off. That's why we look closely at where inclusions sit before recommending a stone for a ring.
Rubies, sapphires and emeralds: what good looks like
Ruby
The most prized rubies are a strong, pure red, sometimes with a slight purplish tint. You'll hear "pigeon blood" used for the very finest, though labs apply the term to strict criteria and some sellers use it loosely. Myanmar (Burma) is the classic source; Mozambique now supplies many fine stones. Orange or brownish tints usually lower value. We only look to source vibrant and well-cut rubies for our customers.
Sapphire
For blue sapphire, look for a rich, velvety mid-tone blue that stays blue in indoor light. "Cornflower" and "royal blue" describe the lighter and deeper ends of the top range. Kashmir, Madagascar and Sri Lanka are the famous origins. Sapphires also come in pink, yellow, green and the pink-orange padparadscha.
Emerald
Look for an intense green with a slightly bluish tint and good transparency. Some visible jardin is normal and expected. Colombian emeralds are known for a warmer, pure green; Zambian stones often have a darker, bluer green. Both can be excellent. The degree of oiling or filling has a big effect on value, so ask about it for every emerald.
What about diamonds?
Diamonds are judged differently from coloured stones. They're graded on fixed, internationally recognised scales rather than by eye and experience alone.
The 4Cs are standardised. Colour is graded from D (colourless) to Z, and clarity from Flawless to I3. Two diamonds with the same grades from the same lab are directly comparable, which is rarely true of rubies or emeralds.
Less colour is better. In a white diamond, the less colour the better. That's the reverse of coloured stones, where richer colour usually means more value. Fancy coloured diamonds, such as yellow, pink and blue are the exception.
Cut drives sparkle. Diamonds are cut for brilliance, and cut grade has a bigger effect on how they look than with most coloured stones.
Certificates are the norm. For any significant diamond, expect a report from a lab such as GIA, IGI or HRD.
Lab-grown diamonds are now very common. They're physically identical to mined diamonds but cost far less. Their prices have fallen sharply in recent years, and resale value is minimal.
Diamonds also often frame a coloured centre stone, as in a sapphire cluster ring or an emerald halo. Then the two have to be matched for colour and quality. We also stock yellow diamond jewellery and lab-grown diamonds. For more, read Sebastian's Complete Guide to Diamond Engagement Ring Buying and our Diamond vs Gemstone Grading guide.
Beyond the big three
We also source and set a wide range of other gemstones. Many offer beautiful colour at a lower price than a ruby, sapphire or emerald of similar size. What matters most is matching the stone to how it'll be worn.
| Gemstone | Hardness (Mohs) | Everyday ring? | Worth knowing |
|---|---|---|---|
| Aquamarine | 7.5–8 | Yes | Clean, pale-to-mid blue; deeper blues are usually heat treated. |
| Tourmaline | 7–7.5 | Yes, with care | Comes in almost every colour, including bi-colour stones. |
| Tanzanite | 6–6.5 | Occasional wear | Striking violet-blue; almost always heat treated. Best in earrings and pendants. |
| Opal | 5.5–6.5 | Occasional wear | Delicate and sensitive to knocks and sudden temperature change. |
| Pearl | 2.5–4.5 | Occasional wear | Organic and soft. Put pearls on last, after perfume and hairspray. |
If you're after a particular stone, book an appointment and we'll talk you through the options.
Natural or lab grown?
Choose natural if rarity and long-term value matter to you. Choose lab grown if you want the look for less and won't be selling it on.
Lab-grown stones cost a fraction of the price of natural stones with similar colour and clarity. They have very little resale value.
Natural stones are priced on rarity. A fine untreated natural sapphire has held its appeal for centuries; a lab-grown one is a beautiful object but not a scarce one. We work with both natural and lab grown stones and we'll always tell you plainly which you're looking at.
Origin, certificates and resale
We recommend an independent lab report for any natural ruby, sapphire or emerald costing more than £10,000, and for any stone sold on a claim of origin or of being untreated.
Origin. A fine stone from Kashmir, Myanmar or Colombia can carry a real premium. But origin is a bonus, not a guarantee of quality. An average Burmese ruby is still an average ruby. Origin can only be confirmed by a lab, and even then it's an expert opinion rather than a certainty. It is not uncommon for certain high-value gemstones to come with more than one laboratory report.
What a lab report tells you. A report from a respected independent lab, such as GIA, SSEF, Gübelin, GRS or AGL, typically confirms:
- what the stone is, with its weight and measurements
- whether it's natural or lab grown
- any detectable treatment, and often how much
- an opinion on origin, where the lab offers one
What it doesn't tell you. A lab report says nothing about price. That's the job of a valuation from an independent valuer, which estimates value for a particular purpose at a particular date. An insurance valuation is usually set at replacement cost, which is often well above what you'd get if you sold.
Resale. A good report makes a stone easier to sell, because a buyer knows exactly what they're getting. It doesn't guarantee a price. Keep the report, your receipt and any provenance notes together. For more on how reports work, see our Diamond vs Gemstone Grading guide.
Questions to ask any seller
Whoever you buy from, an established jeweller should answer all of these without hesitation:
- Is this stone natural or lab grown?
- Has it been treated, and how?
- Is there an independent lab report, and from which lab?
- What are its exact weight and measurements?
- Is it suitable for how I plan to wear it?
How we source: emeralds from Hong Kong
The best stones rarely reach a shop window. They change hands between dealers who know each other, often over many years. That's where four decades of relationships make a difference.
At the Hong Kong jewellery show, our first exhibition of 2026, a customer asked us to find a matched pair of emeralds for earrings, around 1.5ct each, in a bright, slightly bluish green, ideally Zambian to match a pendant she had already purchased.
Over six days we viewed roughly 40 pairs from 8 dealers, several of whom we have bought from for 20+ years. Most didn't make the cut:
- Some had good colour but fractures near the girdle, risky in a setting.
- A few beautiful single stones simply couldn't be matched.
- Others just simply didn’t match the pendant which was of high quality.
We came home with two shortlisted pairs, and had them shipped from New York and Israel for the customer to view. They chose one of the pairs and the earrings are now being made in 18ct white gold settings.
That's the job: not finding an emerald, but finding the one that's right for that person and that piece.
What happens when you ask us to find a stone
A conversation. In the shop, by phone or by video, we talk through the stone, the piece, how you'll wear it and your budget. There's no charge or obligation at this stage.
The search. We contact our dealers and, where it makes sense, look in person on buying trips to Bangkok and at exhibitions such as Hong Kong.
A shortlist. We show you 2–3 options with photos, videos and our honest view of each. Where possible, you see them in person before deciding.
Your decision. To proceed with any bespoke commission we ask for a 50% deposit to confirm your item. For higher-value stones, we can arrange an independent lab report before you commit.
The setting. If the stone is for a bespoke piece, we move straight into design.
Designing around your stone
Once the stone is chosen, the setting should protect it and show it off. That might mean a rub-over setting for an emerald worn daily, or open claws to let light into a sapphire. We'll talk through metal, proportions and practicalities. Every piece is then made in Birmingham. See our Bespoke Jewellery Design service, or browse our Gemstone Jewellery for ideas.
Caring for your gemstone
Rubies and sapphires: warm soapy water and a soft brush. Ultrasonic cleaners are usually fine, unless the stone is fracture-filled.
Emeralds: a damp cloth only. Avoid ultrasonic and steam cleaners, hot water and harsh chemicals, which can draw out the oil.
All stones: have the claws checked once a year. We do this complimentary for jewellery purchased from us.
Frequently asked questions
What matters most when buying a coloured gemstone?
Colour, followed by clarity and cut. Treatment and origin then affect the price.
Are natural gemstones better than lab grown?
They're rarer and hold their value better. Lab-grown stones look the same and cost far less.
Does every gemstone need a certificate?
No. We recommend one for natural stones above £10,000, or where a claim about origin or treatment affects the price.
Does a certificate guarantee value?
No. It confirms what the stone is; a valuation estimates what it's worth.
Can you find a specific stone for me?
Yes. Tell us the colour, size, shape and budget, and we'll search our network.
How long does sourcing take?
Usually 1–6 weeks, longer for rare stones or matched pairs.
Start your search
If you have a stone in mind, or only a colour, book an appointment at our Solihull, Chester or Birmingham Jewellery Quarter store, or call us on +44 (0) 121 200 3308. We'll tell you honestly what's possible within your budget.
