I’ve had several LED purchases that were LEDs of poor quality, actually factory rejects. The sellers may not have known that the LEDs had “chipped chips” missing a piece, or bubbles or inclusions, but even more commonly, the LED chip is off center so the beam pattern is distorted. I let the sellers know, and they made good on fixing the problem.
The reason why I bring this up is that a lot of the LEDs that are sold at prices that are not much lower than the going prices, are actually ‘seconds’ or worse. I just put a kit together and it has four red 3mm LEDs and they really aren’t even indicator grade. The one for the power on LED was so dim I had to replace it, and the red high brightness LED I used was dozens of times brighter even though the current is only a milliamp. So the only way you should buy LEDs is on tape and reel. That way, you know you’re getting parts that have not been tested and rejected. But even that may be too optimistic.
