diamond tester
Skip itA concentrated shelf (top 5 take 91% of clicks) — this niche doesn't clear our bar today.
Quality gap
Great4.1★avg incumbent rating — lower means beatable quality
Avg price
Great$20.17avg listing price — sweet spot $15–$100
Market size
Great$1.3M$1.3M/yr · 937K searches
Price range
Great$8.96–$37.93cheapest to priciest tracked listing — scored on the share inside $15–$100
Conversion
Good6.7%search→purchase rate — share of searches ending in a sale
Review moat
Okay2,273.75avg incumbent reviews — the moat a new listing must climb
Returns
Bad5.8%return rate — above 5% kills the launch gate
Growth
Bad-14.2%90-day search growth — must beat 0% to launch
Brand share
Bad94%top-5 brand share — brand-locked demand
Competition
Bad91%top-5 click share — a locked-up shelf
According to Flapen's Amazon United States niche tracking, diamond tester is a $1.3M/yr Amazon United States market (937K searches/yr). The top 5 brands hold 94% of demand. Verdict: Skip it — 46/100.
Data updated Jul 6, 2026 · scored weekly · How we score niches
diamond tester market data
- Units sold / yr
- 50K–60K
- avg 6,000–8,000/product
- Revenue / yr
- $1.0M–$1.2M
- units × avg price
- Conversion rate
- 6.7%
- Avg BSR
- #8
- Page quality
- 0%
- Prime
- 100%
- Sponsored
- 100%
- Out of stock
- 0.0%
- Avg brand age
- 44 months
- Avg seller age
- 182 days
Competition & brand share
The top 5 products capture 91% of clicks — a locked-up shelf that new listings rarely crack.Brands
7 flat
Sellers
10
Top-5 brand share
94%
Top 20: 100%
Top-5 click share
91%
Top 20: 100%
Open market
3%
- HMKIS45%
- Hqdz18%
- Siziviki16%
- Valkynos11%
- Marvelity4%
- Hqdz-td3%
- Open — no brand owns it (1 brand, 3%)
Demand & seasonality
Weekly Amazon search volume, last 109 weeks — -14.2% search growth over the last 90 days.No pronounced peak months · busiest ÷ quietest = 1.4×
Top diamond tester search terms
- diamond tester599K/yr
- diamond tester pen109K/yr
- diamond tester professional40K/yr
- dimond tester25K/yr
- diamond detector21K/yr
- moissanite tester19K/yr
- diamond tester for jewelry18K/yr
- diamond selector 210K/yr
- diamond and moissanite tester9K/yr
- diamond tester.14K/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 8 tracked products in this niche — three views at once, no toggling.
Top sellers
by 90-day click share
HMKIS Diamond Tester Pen with 60X Jewelry Loupe Magnifier
HMKIS$16.964.1★8,410 rev
Siziviki Diamond Tester Pen Pro High Accuracy Jewelers Gemstone Detector
Siziviki$10.784.1★1,016 rev
Diamond Tester High Accuracy Jewelry Diamond Tester Professional Diamond Tester Pen Jeweler Tool for Novice and Expert - Diamond Selector II 9V Battery Included(Black Diamond Testers)
Hqdz$15.104.1★7,555 rev
Valkynos Professional Diamond Tester Pen with 365nm UV Light & Thermal Sensor Fast 0.5s Detection Portable Gem Checker for Novice & Experts Battery Included
Valkynos$33.164.3★222 rev
Diamond Tester Pen High Accuracy Jewelry Tester Battery Included Gemstone-Only Detection - No Metal/Gold Testing for Novice and Expert Gemologists
Marvelity$8.963.5★42 rev
Newest
by launch dateDiamond Tester Pen High Accuracy Jewelry Tester Battery Included Gemstone-Only Detection - No Metal/Gold Testing for Novice and Expert Gemologists
Marvelity$8.9642 rev
Valkynos Professional Diamond Tester Pen with 365nm UV Light & Thermal Sensor Fast 0.5s Detection Portable Gem Checker for Novice & Experts Battery Included
Valkynos$33.16222 rev
Diamond Tester Pen Jewelry Diamond Tester Pen+30X 60X Mini LED Magnifying Jewelry Eye Loupe Jewelry Distinguish Tool Professional Diamond Selector for Novice and Expert
Hqdz$22.9089 rev
Diamond Tester High Accuracy Diamond Tester Pen Environmental Protection 9V Battery Professional Diamond Selector for Jeweler Novice and Expert Thermal Conductivity Meter (Diamond Tester)
Hqdz-td$15.57117 rev
Purity Testing Kit for Diamonds Gemstones Moissanites Gold Silver and Platinum Jewelry Electronic Digital Diamond Tester Machine JSP GTE
GTE$37.93739 rev
Trending
90-day click momentumDiamond Tester Pen High Accuracy Jewelry Tester Battery Included Gemstone-Only Detection - No Metal/Gold Testing for Novice and Expert Gemologists
Marvelity$8.963.5★
Purity Testing Kit for Diamonds Gemstones Moissanites Gold Silver and Platinum Jewelry Electronic Digital Diamond Tester Machine JSP GTE
GTE$37.934.3★
Valkynos Professional Diamond Tester Pen with 365nm UV Light & Thermal Sensor Fast 0.5s Detection Portable Gem Checker for Novice & Experts Battery Included
Valkynos$33.164.3★
Siziviki Diamond Tester Pen Pro High Accuracy Jewelers Gemstone Detector
Siziviki$10.784.1★
Diamond Tester High Accuracy Jewelry Diamond Tester Professional Diamond Tester Pen Jeweler Tool for Novice and Expert - Diamond Selector II 9V Battery Included(Black Diamond Testers)
Hqdz$15.104.1★
What buyers say about diamond tester
What buyers praise and complain about, mined from review topics.What buyers love
“Easy to handle”
“A great quality tool that is very reasonably priced”
“good value for money”
“Seems like it works”
“It works ok”
“Simple instructions and easy to use”
“The pen is lightweight”
“Its made very durable”
“Perfect size”
“This is good to have especially after having repairs done”
What buyers complain about
“Low quality product”
“Not even functional”
“Doesn't last”
“Not worth 10 bucks”
“Accuracy was not perfect”
“is not convenient to use”
“No decent instructions”
“Short battery life”
“No es como lo describes”
“Did I receive a defective product”
Top return reasons
Common questions
- Is diamond tester profitable to sell on Amazon United States?
- The niche generates $1.3M/yr across 8 tracked products. 1 of 1 products launched in the last 360 days are still selling. 90-day search growth is -14.2%. Flapen's verdict: Skip it (46/100).
- How competitive is the diamond tester niche?
- 7 brands and 10 sellers compete. The top 5 products take 91% of clicks and top 5 brands hold 94% of demand.
- What do buyers complain about in diamond tester?
- Top complaints mined from reviews: Quality-Overall, Functionality-Overall, Durability. The return rate is 5.8% — above our launch gate.
- When does demand for diamond tester peak?
- Demand is steady year-round — the busiest month runs 1.4× the quietest.
- What does it cost to enter the diamond tester niche?
- Listings span $8.96–$37.93; the average listing price is $20.17 (sweet spot $15–$100). The average incumbent carries 2,274 reviews — the moat a new listing must climb.