diamond tester
Worth a lookShows beatable incumbent ratings (3.8★), but a small market ($50K/yr) keeps it on the watch list.
Quality gap
Incredible3.8★avg incumbent rating — lower means beatable quality
Review moat
Great245.61avg incumbent reviews — the moat a new listing must climb
Price range
Great£6.35–£55.37cheapest to priciest tracked listing — scored on the share inside $15–$100
Avg price
Good£14.58avg listing price — sweet spot $15–$100
Conversion
Good6.4%search→purchase rate — share of searches ending in a sale
Brand share
Good63%top-5 brand share — brands hold most of the demand
Returns
Okay3.4%return rate — above 5% kills the launch gate
Competition
Okay61%top-5 click share — leaders hold, buyers still browse
Market size
Bad£50K£50K/yr · 54K searches
Growth
Bad-23.4%90-day search growth — must beat 0% to launch
According to Flapen's Amazon United Kingdom niche tracking, diamond tester is a £50K/yr Amazon United Kingdom market (54K searches/yr). The top 5 brands hold 63% of demand. Verdict: Worth a look — 50/100.
Data updated Jul 22, 2026 · scored weekly · How we score niches
diamond tester market data
- Units sold / yr
- 3K–4K
- avg 100–250/product
- Revenue / yr
- £44K–£58K
- units × avg price
- Conversion rate
- 6.4%
- Avg BSR
- #232
- Page quality
- 0%
- Prime
- 100%
- Sponsored
- 94%
- Out of stock
- 16.4%
- Avg brand age
- 40 months
- Avg seller age
- 276 days
Competition & brand share
The top 5 products take 61% of clicks — established leaders, but buyers still shop beyond them.Brands
16 flat
Sellers
25
Top-5 brand share
63%
Top 20: 100%
Top-5 click share
61%
Top 20: 100%
Open market
31%
- JZK21%
- QWORK15%
- Vakler10%
- luolety10%
- DUSEKI7%
- NIUPIKA6%
Demand
Weekly Amazon search volume, last 25 weeks — -23.4% search growth over the last 90 days.Top diamond tester search terms
- diamond tester41K/yr
- diamond tester professional9K/yr
- diamond tester pen3K/yr
Top diamond tester products on Amazon
Each bubble is one product — market share against review moat; bubble size tracks estimated sales, color grades how beatable the incumbent looks.
All 18 tracked products in this niche — three views at once, no toggling.
Top sellers
by 90-day click share
JZK Portable Electronic Diamond Tester Pen for Diamond Sapphire Ruby Crystal Agate Jade gems Multi Gemstone Precious Stones Hardness Test Tool Diamond Selector II V2
JZK£10.584.0★2,811 rev
QWORK Electronic Diamond Tester Portable Electronic Gemstone Tester Pen for Diamonds Sapphire Ruby Crystal Agate Jade
QWORK£8.574.0★64 rev
Portable Electronic Diamond Tester Pen Professional Moissan Diamond Tester High Accuracy Jewelry Detector for Diamond Jade Ruby Crystal Sapphire Agate gems Multi Gemstone Precious
Vakler£8.103.9★19 rev
Portable Electronic Diamond Tester Pen High Accuracy Jewelry Diamond Selector Detector with 2Pcs 30X 60X Mini Led Foldable Magnifying for Novice Expert
luolety£15.723.9★120 rev
Electronic Diamond Tester Pen Portable Professional Jewelry Gemstone Testing Tool for Diamond Sapphire Ruby Crystal Agate Jade gems Multi Gemstone Precious Stones with LED Light and Audio Indicator
DUSEKI£7.672.9★10 rev
Newest
by launch date
Portable Electronic Diamond Tester Pen Kit Electronic Gemstone Detector
VivaStride£9.271 rev
Portable Electronic Diamond Tester Pen High Accuracy Moissan Diamond Jewelry Detector Stones Hardness Testing Gemstone Selector Tool for Sapphire Ruby Agate Jade Crystal Multi Gems
Ignara£7.914 rev
Portable Electronic Diamond Tester Pen Professional Moissan Diamonds Tester High Accuracy Jewelry Detector with LED Light for Diamond Jade Ruby Crystal Sapphire Agate gems Multi Gemstone Precious
poluu£7.262 rev
Electronic Diamond Tester Pen Portable Professional Jewelry Gemstone Testing Tool for Diamond Sapphire Ruby Crystal Agate Jade gems Multi Gemstone Precious Stones with LED Light and Audio Indicator
DUSEKI£7.6710 rev
Electronic Diamond Tester Pen Professional Moissan Diamond Jewelry Detector Portable Gemstone Selector Tool for Sapphire Ruby Crystal Agate Jade Gems Precious Hardness Test Tool High Accuracy II V2
Draymora£7.774 rev
Trending
90-day click momentumPortable Electronic Diamond Tester Pen Kit Electronic Gemstone Detector
VivaStride£9.273.0★
Portable Electronic Diamond Tester Pen High Accuracy Moissan Diamond Jewelry Detector Stones Hardness Testing Gemstone Selector Tool for Sapphire Ruby Agate Jade Crystal Multi Gems
Ignara£7.914.7★
Portable Electronic Diamond Tester Pen Professional Moissan Diamonds Tester High Accuracy Jewelry Detector with LED Light for Diamond Jade Ruby Crystal Sapphire Agate gems Multi Gemstone Precious
poluu£7.264.0★
Portable Electronic Diamond Tester Pen High Accuracy Jewelry Detector Moissan Tester Professional Testing Diamond Gems Tool for gems Multi Gemstone Precious Jade Ruby Crystal Sapphire Agate
Brightora£7.282.5★
Portable Electronic Diamond Tester Pen High Accuracy Jewelry Diamond Selector Detector with 2Pcs 30X 60X Mini Led Foldable Magnifying for Novice Expert
luolety£15.723.9★
What buyers say about diamond tester
What buyers praise and complain about, mined from review topics.What buyers love
“Works well”
“Works brilliant and easy to use”
“Good quality”
“is incredibly affordable”
“perfect worked as it should”
“the item is very lightweight”
“nothing spilled”
“the audio beep/LED display gives you an instant answer”
What buyers complain about
“But I have to say that the instructions could really offer better advice”
“Very badly made”
“Faulty”
“Did not work”
“Very erratic similar to how previous similar models end up after 6 months use”
“then false negative on a GIA certificated diamond so unfortunately I will have to return it”
“I assume they were leaking”
“Complete waste of money”
“Broke on first use”
“The bottles were wet”
Top return reasons
Common questions
- Is diamond tester profitable to sell on Amazon United Kingdom?
- The niche generates £50K/yr across 18 tracked products. 0 of 8 products launched in the last 360 days are still selling. 90-day search growth is -23.4%. Flapen's verdict: Worth a look (50/100).
- How competitive is the diamond tester niche?
- 16 brands and 25 sellers compete. The top 5 products take 61% of clicks and top 5 brands hold 63% of demand.
- What do buyers complain about in diamond tester?
- Top complaints mined from reviews: Instructions/User Manual/Troubleshooting, Quality-Overall, Defective Material/Parts. The return rate is 3.4%.
- What does it cost to enter the diamond tester niche?
- Listings span £6.35–£55.37; the average listing price is £14.58 (sweet spot $15–$100). The average incumbent carries 246 reviews — the moat a new listing must climb.