what is the highest grade/field strength magnet in the market?

[eddywind]

more information:

there are different grade NdFeB magnets, now, only M magnets could be  "50" or higher.
but one problem is the temperature coeffient. usually we do not use N or M magnets, H magnets are needed at least.

for example, if you make a motor with N55magnet, when the temperature is changing, the magnetic field strength change a lot also.

[jadaro2600]

Rare earth magnets seem to recover from heat better than neomags - according to some sources ( Samarium Cobalt for example ).

Not always cost friendly - but neither are neomags.

[SomedayIsle]

I found some YT's a few years ago through alibaba...they were being sold in a product called the 'battery doubler'.  Definitely more powerful than NdFeB's for commensurate size.  Too bad they aren't allowed a bigger audience.  I'm stumped as to why they are not now widely available.....



hmmm

[khabe]

Rare earth magnets seem to recover from heat better than neomags - according to some sources ( Samarium Cobalt for example ).
Not always cost friendly - but neither are neomags.

Rare-earth magnets are made from alloys of rare earth elements.
Neodymium magnets are the strongest and most affordable type of rare-earth magnet. Neodymium alloy (Nd2Fe14B) is made of neodymium, iron and boron.
Samarium-cobalt magnets (chemical formula: SmCo5) are less common than Neodymium magnets because they are more expensive to produce and create a weaker magnetic field than Neodymium magnets. However, Samarium-cobalt magnets have a relatively high Curie point, which makes them suitable for high-temperature environments.
( http://en.wikipedia.org/wiki/Rare-earth_magnet )

True Gaussmeter costs a lot of,
Methodology how to meter  ... how its calibrated ...
Not every time you receive your magnets as strong as described, as well as described grade - you can easily examine (and often sacrify using hot water up till boiling 
Sometimes List of magnets for sale changes by stream of fashion
Myself I do not worry about is it 50 ... 48 ... 45 or 44 ... it does not matter mach - true Grade and precision geometry are principals when building some machine,
Of course I buy and try every newby "high_end_grade" as well.
Good luck,
be strong,
khabe

[khabe]

What's the strongest magnet known in the Universe?
The answer is the magnetar, a rare type of neutron star.
...
Get much closer, and the magnetic force will rearrange the atoms in your body.
http://www.gsfc.nasa.gov/scienceques2003/20040206.htm

cheers,
khabe

The theoretical limit for neodymium magnets is grade N64