Looking at 100 watt medium based lamps for my home office. I'm assuming I want ceramic as opposed to quartz, and a 3K color temperature.

Of the major brands, which looks most like incandescent light? Someone else commented that Philips has a decidedly pink cast; I have a Cosmo lamp where that is noticeable so I'm assuming their other lamps are similar. Is the hue of say GE lamps any better?

The Philips Mastercolor 4000K lamps are the best if you want that halogen/incandescent color, I currently use the Mastercolor 4000K CDM (100w) in my living room in a torchiere uplighter and the CRI and color quality is pretty incredible and nearly identical to quartz halogen. Do not get the 3000K version, they are VERY warm and give a slight orangy-pink hue similar to a 2700K CFL. All ceramic MH lamps run warmer than their rated K-temp, I have yet to find a 4000K CMH that runs as cool as a 4000K quartz MH. Warm white quartz MH (3000K) are also pretty bad when it comes to emulating halogen, the Sylvania 100w metalarc is a protected 3000K lamp and it burns VERY pinkish orange, the CRI is also pretty bad as well. So stay with CMH.

4000K isn't the color of halogen lamps. Most 3000K CMH lamps I've seen, have exactly the same color as halogen. These are the quartz warm white MH lamps such as my Osram HQI-TS 70W/WDL which have pinkish hue.

Are the non-elite 4K versions of the Philips MasterColor any good? They seem to be much more common and inexpensive than the Elite versions. Is there a particular date range to look for; looks like the same lamp has a bunch of different arc tube styles and countries of manufacture.

I would say anything Philips MasterColour that is not Chinese would be best. As for the arc tube design, the ball shaped ones have shorter warmup and hot restrike times, but other than that I don't think there is any significant difference. The newer ones all have a ball shaped arc tube and the older ones have a cylindrical arc tube.

I have a 4000K and a 3000K that I change periodically when I want different colours. I do find they appear at a lower colour temperature than other sources.

The ball shape offers longer life (there is less of the liquid halide pool when running, so less of the alumina may dissolve in it), better light distribution around the lamp (the cylinder sides block quite some light, compare to the thin side sections) and higher efficacy (for a 70W lamp it is usually about 7000lm with the ball instead of 6000lm with the cylinder).

But the differences are not that huge, compare to a difference what the CMH (assume quality product) offers over QMH...

I have some 3000k CMH lamps and the color is identical to a halogen lamp. The 4000k CMH lamps are not cool or warm, they are just plain white.

When I put a quartz halogen flood side by side with my Philips 4000K CDM lamp I cannot tell the difference, the color is so close. But the 3000K version is noticeably warmer than the halogen. I understand Halogen is rated well below 4000K, but for whatever reason the kelvin ratings of Philips CDM lamps are considerably off. A 4000K quartz MH looks almost daylight compared to the CDM 4000K. Im not sure what you mean by "Elite" version, but the lamps I have are all made in the USA and use the cylindrical arc tube.

I have a cylindrical arc tube 35W CDM (MasterColour Elite) made in Belgium. The colour temperature is not constant. Sometimes it is lower than 4000K, sometimes it is just at 4000K. It is rated at 4000K. I notice that if there are lots of purple or pink flashes during the warmup, it ends up being more 3600-3800K and if the warmup is uneventful, it is closer to 4000K.

Halogens are somewhere between 2800 and 3000K. It is physically impossible to make tumgsten filament lamps above 3695K, because there the tungsten just melts. There are lamps operating at 3500K or so, but these have rated life of about 25hours or so, so are only usable for special instruments.

With CMH I have experience with Osram Powerballs (the first affordable ball shaped CMH's on the market; it seems all the others are just copy of the Osram design) and I could tell the color at nominal power is just impressive, both 3000K (these are rated just 80CRI), as well as 4200K (these are rated CRI 95+) versions. When underdriven (dimmed to about 60% of the rated current, but always with at least 5minutes warmup at full power), the 3000K turns very slightly greenish tint 4000K, the 4200K version becomes a bit pinkish and about 5000K or so. Neither of these lamps was rated as dimmable.

The cylindrical I have just one 35W 3000K GE and that is a bit off, but it may be due to an unknown wear.

The one QMH looks really awful compare to the CMH's. It is still around 300K, but it is really unnaturally yellow and the red rendering is awful (the red test wires I have on m y desk really look dark grey; with the CMH they are nice red, really llke with the daylight)

Wound up buying a Philips MHC100/U/M/4K, made in US with a 2001 date code and the cylindrical arc tube.

Wound up buying a Philips MHC100/U/M/4K, made in US with a 2001 date code and the cylindrical arc tube.

Where did you get it?

$12.00 shipped on eBay.

You'll like it.

Better one that have a spherical arctube. The cylindrical arctubes takes 15 mins of cooling down before hot restrike compared to 3-5 mins for spherical arctubes. the spherical arctubes runs up faster and have better CRI.