On Android, I use SD insight for a first test that most of the time whether the card is a forgery or not, just by observing its data from the manufacturer, date of manufacture, etc. I've already returned several. On this map, I see Samsung and consistent manufacturing details. Positive Test.
To test the speed you need a USB 3 (I use a Transcend USB Card Reader Transcend TS-3 RDF5W card reader SD / Micro SD USB 3.0 White).
My tests are now on a good laptop (I7 quad-heart, 16 Gb RAM and a USB card reader 3 USB 3 (not on the SD internal drive of the laptop, although slower than USB 3).
I now use Windows H2testw to check my micro sd cards before using them. At least one complete pass writing + reading.
I highly recommend this free program, because it helps to fully test the card (too many fakes are on the market), even with the same reference. The fake cards and those of bad quality is usually not resist a simple background to test on a USB drive 3 (that's hard heat map to literally and figuratively). Transcend player reached nearly 60 ° C at the heart of the test.
A reformatted to NTFS micro sd:
I observe a write speed of 19.3 MB / s on average total write 64 GB; which is perfect for 20 MB / s max advertised (the card reached the moment). Obviously copy smaller files will always be slower. There is a test under optimum conditions. To transfer a few GB of videos, one should approach those numbers.
Read Samsung announces 70 MB / s, I observe, always with H2testw a read speed of 61.4 MB / s. A great result.
Tested on multiple tablets without problems (ME302c Asus, Toshiba Excite AT 110-A, Nexus 7, 2013 TBT).
Obviously the results are highly variable depending on the tablet reader. For example it is quite unnecessary to use this card only on the Toshiba Excite AT-110 A, which is the internal Micro SD reader that limits perfs of the card).
