According to certain aspects, reaction conditions in a process for making quantum dots are provided where phosphine components in the reaction mixture are substantially completely reacted or otherwise used during the process such that free or unreacted or unbound phosphonic acid or metal phosphonate species or byproducts thereof are absent or substantially absent in the reaction mixture when quantum dots of desired size are obtained. According to certain aspects, reaction conditions in a process for making quantum dots are provided where phosphine components in the reaction mixture are absent such that free or unreacted or unbound phosphonic acid or metal phosphonate species or byproducts thereof are absent or substantially absent in the reaction mixture when quantum dots of desired size are obtained. When making quantum dots using phosphonic acid or metal phosphonate species resulting in bound phosphonic acid or metal phosphonate species, such bound phosphonic acid or metal phosphonate species may be removed and/or diluted away such as by using a metal carboxylate species during a high temperature coating process resulting in quantum dots which lack or substantially lack phosphonic acid or metal phosphonate species on their surface as bound ligands. Such quantum dots may include II-VI core quantum dots characterized as yellow, orange or red emitters which may be larger in size than quantum dots characterized as green or blue emitters or emitters having an emission of less than 530 nm. According to certain aspects, low energy emitters such as yellow, orange or red quantum dots are made by growing II-VI core quantum dots and substantially completely consuming phosphonic acid or metal phosphonate species in the reaction mixture. Once such cores are precipitated out of solution, there are substantially no phosphonic acid or metal phosphonate species or byproducts thereof remaining in the reaction solution and accordingly in the core quantum dots prior to the coating process. According to an alternate aspect, smaller cores required for making wider bandgap green and blue emitters are produced by quickly quenching the reaction mixture resulting in a large amount of unreacted phosphonic acid or metal phosphonate species remaining in the reaction mixture and accordingly in the core quantum dots. According to one aspect, the presence of unreacted phosphonic acid or metal phosphonate species in the core quantum dots diminishes the emission of the quantum dots. Accordingly, unreacted phosphonic acid or metal phosphonate species are removed from the quantum dots. Methods according to the present invention are directed to making any band gap or color that can be obtained via size changes of the semiconductor used in the core, for example, all visible colors for CdSe or InP.