When resolution was still stuck at 1080p Full HD, a wide color gamut usually meant covering 95% of the Rec. 709 color range. But with the development and maturation of 4K UHD and 8K UHD resolutions in recent years, the UHD Alliance, with the approval of the International Telecommunication Union (ITU), released specifications for their definition of Ultra HD Premium, requiring that certified equipment cover at least 90% of the DCI-P3 color space.
A “wide” color gamut, however, does not necessarily meet these requirements, because the color gamut’s coverage is more important. In the past when testing color gamut, one would often see the description, “XX% of the NTSC color gamut”. In reality, this type of description was not very accurate because this type of color gamut description was more a measure of area, for example, 100% of the Rec. 709 color gamut is roughly equal to 72% of the NTSC color area but of that number about 4% of the color gamut range is not covered as seen in the image below (the solid line in the image represents the Rec. 709 color gamut, while the dash line represents the NTSC color gamut).
Because of all of this, when a color gamut is said to cover the Rec. 709, DCI-P3, Rec. 2020, or any other color space, it does not necessarily mean that its colors are accurate. More importantly, outside of having just higher coverage, color accuracy needs professional calibration before a projector can truly be called color accurate.