Edmunds Optics has a number of what you want. I would not preclude Chinese optics - you may have a hard time finding a magnifier NOT made in China and some Chinese stuff is just fine.
Optics range from a simple lens, which because of its design will have problems correcting all colors equally, and probably have some other aberrations as well. The Starrett hammers have a simple lens in them. About 1 inch in diameter, and about 50mm focal length, or about 5x magnification.
Going up in quality (and cost), you could get an achromat lens. These are lenses in which two lenses, each from different types of glass (generally called "crown" and "flint") with differing indices of refraction and dispersion are cemented together to create a single lens that corrects for several wavelengths simultaneously. This gives a sharper focus.
But achromats can have other aberrations. For some applications, the spherical lens surfaces are modifed to create "asphericals", that fix those problems. You can get achromat asphericals. Edmund actually makes some of these by casting plastic onto an achromat in an aspherical shape. These would probably make cool magnifiers, but the plastic might not be too durable. Then again, the Starrett magnifier is plastic.
But all that theory may be moot. Generally recognized as the best magnifying lenses are
Hastings Triplets. Edmunds and elsewhere also sell
Machinist's magnifiers, which are several simple lenses in a frame. It is cheaper than a Hastings, and has several different magnfications in the same unit.
I would caution against buying the most powerful magnifier unless you know you need super high magnification. If you go too high you have issues holding the lens and workpiece, and you need beaucoup lighting. I'd go with a 7x, or 10x (40-25mm focal length),
I use an old American Optical Cycloptics (aka "the monster"), which is probably overkill for this, but they are great.
J