Diamond Black Review

In This Review
Performance Tests | Firmness | Support & Sleeping Positions | Design | Materials | Comparisons | FAQs

At NapLab, we put each mattress to the test.

We test 10 different factors that impact the performance, comfort, and feel of the mattress. We then take the results of those tests and compare them to every mattress we’ve tested to date.

Check out the full performance table below to see how this mattress ranks:

Factor	Diamond Black	Average
Overall Score	8.83	8.52
Price (Queen)	$2,999	$1,515 (Hybrid only)
Cooling – Score	9.0	8.6
Sinkage – Depth	2.36″	2.25″
Sinkage – Feel	Deep	Moderate
Motion Transfer – Score	9.3	8.2
Motion Transfer – Acceleration	6.49 m/s²	8.77 m/s²
Response Time – Score	8.9	8.7
Response Time – Mostly Recovered	0.3 sec.	0.4 sec.
Response Time – Fully Recovered	1.1 sec.	1.0 sec.
Bounce – Height	7.53″	8.66″
Bounce – Feel	Low	Moderate
Edge Support – Score	8.6	8.7
Edge Support – Sitting	3.75″	3.85″
Edge Support – Lying	Good	Good
Sex – Score	8.0	8.2
Pressure Relief – Score	10	8.6
Comfort Layer Thickness	6.00″	4.34″
Mattress Thickness	14.75″	12.30″
Off-Gassing – Score	6.1	7.9
Off-Gassing – Smell	Strong	Strong
Off-Gassing – Days	14 days	8 days
Company – Score	7.8	8.8
Trial	120 nights	194 nights
Warranty	20 years	40% have lifetime warranties, average of other 60% of mattresses is 13 years

How is Diamond Black Different?

The Diamond Black is a 14.75″ hybrid mattress with an overall performance level that is better than average, but with a price that is also higher than average.

Advantages

Advantages of the Diamond Black include better cooling, better motion isolation, faster material response time, and exceptional pressure relief.

Neutral Factors

This mattress has deep sinkage and low levels of bounce. Both sinkage and bounce are preferential factors and different sleepers may have different ideas of what is “good” vs “bad”.

If you prefer sleeping “in” the mattress, you are more likely to enjoy the feel of the Diamond Black than if you prefer to sleep “on” top of a mattress.

Disadvantages

The Diamond Black has a slightly lower sex score than average, mostly due to the lower bounce level. It also has slower off-gassing and a lower company score.

The Diamond has a 120-night trial (shorter than average) and also a $99 return fee if things don’t work out.

The Diamond Black has excellent cooling. During our tests, I did not feel any significant level of heat retention around my body. This mattress has a few different materials and design choices that are helping to improve cooling.

First, the mattress cover has a cool-to-the-touch feel. This cooler feel is especially nice when you first get into bed, though it loses some of its cooling feel after lying in the same position for a while.

Beyond the cooling cover, the mattress also utilizes cooling bands, graphene-infused memory foam, and coils. The coils are certainly adding improved airflow and breathability, which is beneficial.

• Baseline Temperature – the temperature of the mattress before anyone lies on it
• Maximum Temperature (0 minute) – the temperature of the mattress after lying on it for 15 minutes
• Ending Temperature (5 minute) – the temperature of the mattress after being lied upon and having no one on it for 5 minutes

In addition, I believe the graphene-infused memory foam is beneficial as well, especially compared to a memory foam without any graphene infusion. All that said, I’m less impressed with the cooling bands.

I’ve tested other mattresses that use similar cooling bands, and in each case, they just don’t seem to make a meaningful cooling difference, at least based on my experiences and testing data.

In my view, the hybrid design, cooling cover, and graphene-infused memory foam are doing the heavy lifting for cooling.

In our objective temperature tests, we measured a max surface level temperature of 90.9° F. This is 0.6° warmer than the average of 90.3° F, based on all of our tests to date.

After getting off the mattress, the temperature declined by 4.5 degrees from minutes 0 to 1, which is 0.3 degrees less cool than the average 0 to 1 minute decline of 4.8 degrees.

When we consider the combination of objective data, my subjective experiences, and an analysis of the materials, I’m confident in my view that cooling is excellent.

The Diamond Black has deep sinkage. During our tests, we measured a pressure point sinkage depth of 2.36″. This is 0.11″ more sinkage than the average sinkage depth of 2.25″, based on all of our tests to date.

The level of sinkage is documented in the image below.

The mattress creates a balanced body contouring hug around the body. Diamond Black utilizes a mix of euro top pillow top, memory foam, poly foam, and coils.

This mix of different materials helps to create a more balanced, even, and less polarizing type of feel. It also helps prevent the memory foam layer from creating excessive hug. In my view, Diamond Black has a feel that most sleepers can enjoy.

The Diamond Black has a very low level of motion transfer. During our tests, we measured a total acceleration range of 6.49 m/s². This is 26% less motion transfer than the average of 8.77 m/s².

This mattress utilizes a 6.0” thick comfort layer, which is considerably thicker than average. All of that extra material helps absorb and disperse energy. In addition, this mattress is equipped with a 2.0” memory foam layer.

Memory foam is especially ideal for energy absorption. All of these foam layers create less bounce than average. Lower bounce means less energy, less energy means less motion transfer.

The level of motion transfer is also documented in the video below.

In our motion transfer chart, which visualizes our accelerometer data, we can see the highest motion peaks from 0 to 0.2 seconds. Motion begins to decline thereafter, but remains a bit spiky through 0.6 seconds (though those levels are still relatively very low).

By 0.92 seconds, we’ve returned to near-zero levels of energy, which is 0.02 seconds longer than the average motion duration of 0.90 seconds.

While motion duration was a touch over average, it’s nothing I’m concerned about, especially with motion intensity being so significantly lower than average.

Overall, I’m pleased with this level of motion transfer and expect it will be more than sufficient for most sleepers.

The Diamond Black is a mixed bag for material responsiveness, with a very fast mostly recovered response time and a moderate fully recovered response time.

In our mostly recovered test, we measured a recovery speed of 0.3 seconds, which is 0.12 seconds faster than the average of 0.42 seconds, based on all of our tests to date.

In our fully recovered responsiveness test, we measured a recovery speed of 1.1 seconds, which is 0.08 seconds slower than the average of 1.02 seconds. Most of the material layers, including the euro top, poly foam, and coils, spring back to their original shapes quickly.

The level of responsiveness is documented in the video below.

For this reason, we see the mostly recovered response time faster than average at 0.3 seconds. However, the full material recovery takes a bit longer, primarily due to the 2.0” memory foam layer.

Memory foam is more viscoelastic and, as such, takes longer to fully recover to its original shape after it has been compressed. While the full material recovery speed is a touch worse than average, I wouldn’t call it slow.

If you’re super sensitive to material responsiveness, you could find these speeds problematic, but for the vast majority of sleepers, these response speeds are fast enough to be a non-issue.

The Diamond Black has a low level of bounce. During our tests, we measured a total bounce height of 7.53″. This is 1.13″ less bounce than the average of 8.66″, based on all of our tests to date.

The lower-than-average bounce is the product of the thicker-than-average 6.00” comfort layer and the usage of 2.00” of memory foam. More foam means there is more material that can absorb and disperse energy.

In addition, memory foam in particular is especially good at absorbing energy.

The level of bounce is also documented in the video below.

This material design means there is less energy to be returned as bounce. The lower bounce does mean sex performance is worse, but a lower bounce also means lower motion transfer.

As a result, there are pros and cons worth considering here.

The Diamond Black has excellent sitting edge support and good lying edge support.

In our sitting edge support test, we measured a sitting sinkage compression of 3.75″. This is 0.10″ less sitting sinkage than the average of 3.85″, based on all of our tests to date.

The level of edge support while seated is documented in the images below.

While lying directly on the edge of the mattress, I felt that the support was good in all sleeping positions. This mattress is equipped with a full perimeter of reinforced support foam along the edge of the mattress.

This reinforcing foam is 3” wide and 8” tall. While this reinforced support foam greatly helps sitting edge support, I’m less thrilled with the lying edge support. The cover of this mattress has a notable curvature downward and away from the edge of the mattress.

This curving design creates a weakening of support along the edge.

The level of edge support while lying is documented in the images below.

To be fair, we tested the lux quilted hybrid version, which uses the quilted cover with the downward curvature. The other versions of the mattress (all-foam and hybrid) do not use a quilted cover and do not have a downward curving edge. I would expect lying support to be slightly better on the all-foam and hybrid version.

All that to say, I’m pleased with the level of sitting edge support, but I think it’s fair to see there is room for improvement when it comes to lying edge support on this mattress version.

The Diamond Black has good sex performance. On the positive side, noise is minimal, pressure relief is outstanding, and cooling is excellent. So if nothing else the mattress is both comfortable and quiet.

In addition, edge support while sitting directly on the edge was also excellent, measuring in at 3.75” of sitting edge sinkage. That’s better than average and a more robust edge support extends the usable surface area of the mattress for amorous activities.

Moving on to the not-so-good stuff, we have bounce, which we measured at 7.53”. This is notably less bounce than average. When it comes to sex, more bounce is almost always better.

Bounce at this level means that sex is more tiring and more strenuous. Any time we see a super thick comfort layer like this one, especially when that comfort layer uses one or more thick memory foam layers, we typically see lower bounce and worse sex as a result.

Sex Factor	Factor Weight	Score	Rating
Bounce	65%	7.2	Moderate
Edge Support	20%	9.1	Excellent
Noise	5%	10	Minimal
Pressure Relief	5%	10	Outstanding
Cooling	5%	9.0	Excellent

As with many performance areas, there are always trade-offs. All of those comfort foams create amazing comfort, pressure relief, and low motion transfer, but they do come at a cost to sex performance.

The Diamond Black has an outstanding level of pressure relief. During our tests, I felt no significant pressure points on my body.

Quite the opposite, I found the Diamond Black to be incredibly comfortable, even while lying in the same positions for extended periods of time.

The mattress is equipped with 6.0″ of comfort material, which is 1.66″ more comfort material than the average comfort layer thickness of 4.34″, based on all of our tests to date.

All of those extra layers go a long way to creating amazing comfort. This mattress uses a mix of different material types, including a pillow top, memory foam, poly foam, and coils.

Those materials create a blended feel that delivers a balanced body contouring hug, reasonably quick material responsiveness (no stuck feeling), and incredible comfort.

The feel is neither too much nor too little. It’s balanced, even, and non-polarizing, the type of feel that many sleepers will enjoy.

In our objective pressure mapping tests, we measured a max PSI of 0.50, which is well within the 1.0 PSI threshold that I ideally want to see for all mattress tests.

Pressure Relief (PSI)	Average	Maximum
Side Sleepers	0.10	0.50

Pressure Relief (PSI)	Average	Maximum
Back Sleepers	0.05	0.50

Pressure Relief (PSI)	Average	Maximum
Stomach Sleepers	0.05	0.27

When I consider our objective pressure mapping tests, material thickness, material quality, and my subjective experience on the mattress, I’m confident most sleepers will find the pressure relief to be outstanding.

The Diamond Black had a strong smell upon the initial unboxing. The mattress smelled for 14 days. This is 6.3 days longer than the average smell duration of 7.7 days.

Diamond mattresses come with a 120-night trial period and a 20-year warranty. Shipping is free. Returns are $99.

Company Factor	Factor Weight	Score	Data
Returns	40%	7.0	$99
Trial Period	30%	8.0	120 nights
Warranty	20%	8.0	20 years
Shipping	10%	10	$0
Country of Origin	0%		USA

Comparing 118+ brands tested to date, the average trial period is 194 nights, 74 nights more than Diamond offers. The average warranty is 13 years, which is 7 years less than the Diamond warranty, and that’s if we exclude the 40% of mattresses that offer lifetime warranties.

The Diamond Black Mattress is available in three distinct firmness levels: Plush, Medium, and Firm. In addition to choosing your firmness, the Diamond Black is manufactured in three different designs: All-foam, Hybrid, and Lux Quilted Hybrid.

Our tests are based on the medium version Luxe Quilted Hybrid.

	All-Foam	Hybrid	Luxe Quilted
Price (Queen)	$2,399	$2,599	$2,999
Thickness	14″	14″	14″
Cover	Cooling Cover	Cooling Cover	Cooling Cover
Contour	More Contour	Balanced Contour	Balanced Contour
Bounce	Less Bounce	More Bounce	Balanced Bounce

Plush Version

While we did not test the Plush or Firm versions, I will give an estimate on both based on my experience and their material designs. I would estimate the Plush version to have a soft feel and a rating of 4 out of 10, where 10 is the most firm.

Medium Version

We tested the Medium version in this review, which has a medium-firm feel, which is a 6 out of 10.

Firm Version

Finally, I would estimate the Firm version to have a firm feel with an 8 out of 10 rating on the firmness scale.

Support on the Diamond Black is outstanding. During our tests, I felt well supported in all sleeping positions. The mattress is equipped with an 8.75″ support layer. This is 0.79″ thicker than the average support layer thickness of 7.96″, based on all of our tests to date.

Support Factor	Data
Comfort Layer	6.00″
Support Layer	8.75″
Firmness	Soft, Medium-Firm, and Firm
Body Contour	Balanced
Zoned Support	No
Reinforced Edge	Yes

For a mattress to create ideal support, it needs to both create a neutral spinal alignment and sufficient comfort. Diamond Black meets both of those requirements with ease. This mattress is available in 3 firmness levels, including plush, medium, and firm.

We tested the medium version and found it has a medium-firm feel, 6 out of 10 on our firmness scale. The medium version is going to be the best choice for the vast majority of sleepers. That said, it’s helpful that other firmness levels and cover types are offered (see our firmness section for more info).

In all mattress tests, we make it a point to cut the mattress open to examine the material quality. As part of these assessments, we use a densimeter to measure foam density and a digital caliper to measure coil thickness.

The 2.0” memory foam layer measured in at a density of 3.66 PCF, which is excellent. Denser foams are typically higher quality, perform better, and last longer. The density of the other poly foam layers was less impressive, ranging from 1.23 to 1.54 PCF. That’s far from ideal.

The coil thickness measured at a 14.5 gauge, which is on the thicker side.

Check out the table below to see the sleeper weights and sleeping positions that would be best suited for this mattress.

Plush Version

Sleeper Weight	Stomach Sleeper	Side Sleeper	Back Sleeper
Under 150 lbs.	Maybe	Yes	Maybe
150-250 lbs.	Maybe	Yes	Maybe
250-300 lbs.	Maybe	Yes	Maybe

Medium Version

Sleeper Weight	Stomach Sleeper	Side Sleeper	Back Sleeper
Under 150 lbs.	Yes	Yes	Yes
150-250 lbs.	Yes	Yes	Yes
250-300 lbs.	Yes	Yes	Yes

Firm Version

Sleeper Weight	Stomach Sleeper	Side Sleeper	Back Sleeper
Under 150 lbs.	Yes	Maybe	Yes
150-250 lbs.	Yes	Maybe	Yes
250-300 lbs.	Yes	Maybe	Yes

The lower-density poly foams do make me a bit worried for longevity, but some of those fears are abated by the thicker wire gauge and 3.66 PCF memory foam layer.

Moving on, this mattress does not use zoned support. Instead, we have a consistent firmness from head to foot.

Based on all of my tests to date, an analysis of the materials, and my subjective experiences, I’m confident that most sleepers will find support on the Diamond Black is outstanding.

The Diamond Black is a 14.75″ hybrid mattress that comes in three firmness options—Soft, Medium-Firm, and Firm.

Design Factor	Data
Type	Hybrid
Thickness	14.75″
Cover Type	Pillow Top
Weight	Not Available
Has Handles	Yes
Fiberglass-Free	Yes
Ships in a Box	Yes

It is designed to have a high-profile look and a pillow top design. This gives the Diamond a luxury look, much like the type of traditional hybrid you’d see in a hotel.

The Diamond Black is 14.75″ thick and contains a combination of different foam types and a pocketed coil base. From top to bottom, here is a full list of the materials used in this mattress:

Layer Type	Thickness	Manufacturer’s Specs	Tested Specs
Pillow Top	3.00″	Not Available	1.23 PCF
Memory Foam	2.00″	Not Available	3.66 PCF
Poly Foam	0.75″	Not Available	1.54 PCF
Poly Foam	0.25″	Not Available	1.34 PCF
Pocketed Coils (Interior), Poly Foam (Edge)	8.00″	Not Available	14.5 Gauge, 2.07 PCF
Support Foam	0.75″	Not Available	1.54 PCF

The Diamond Black has a 3.0″ pillow top cover. Diamond describes this cover as a cool-to-the-touch “Ultra Cool Cover” designed for maximum heat dissipation.

It has diagonal stitching and quilted tufted accents for an aesthetic that is a blend between modern patterns and more traditional processes.

The comfort layer is 6.00″ thick, which includes the thickness of the pillow top. Below the pillow top is a 2.00″ memory foam layer (gray foam) followed by two layers of poly foam.

Directly below the memory foam is a 0.75″ poly foam and below that layer is a thinner 0.25″ poly foam. These foam layers work together to provide comfort and transitional support for better pressure relief.

The support layer is 8.75″ thick and made of an 8.0″ pocketed coil system. This system individually encases each coil in a thin fabric, which enables the coils to operate more independently of each other.

Compared to a traditional innerspring design, this approach improves pressure relief and also helps to limit motion transfer.

Product Evolution

The Diamond Black was released in July 2024 at the Summer Las Vegas Market, one of the largest mattress conventions held twice each year in the US.

In January 2025, Diamond expanded their collection to include 9 total mattresses, a mix of foam and hybrid options.

To date, we have not documented any major changes made to the mattress since its original launch date.

Other Mattresses to Consider

Not sure if the Diamond Black is the right pick for you? Check out these three other top-rated hybrid mattresses for alternatives you may want to consider.

Frequently Asked Questions

Still have questions? Check out some of the top FAQs on the Diamond Black mattress below and get the answers you’re looking for.