In another article Gemination is described as:Varieties of Modern Greek wrote:■ Geminate consonants. Most Modern Greek varieties have lost the distinctively long (geminate) consonants found in Ancient Greek. However, the dialects of the south-eastern islands, including Cyprus, have preserved them, and even extended them to new environments such as word-initial positions. Thus, the word <ναι> 'yes' is pronounced with a distinctively long initial [nː] in Cypriot, and there are minimal pairs such as <φύλλο> [ˈfilːo] 'leaf' vs. <φύλο> [ˈfilo] 'gender', which are pronounced exactly the same in other dialects but distinguished by consonant length in Cypriot.
There is a discrepency in the description of the Cypriot dialect there. In one case gemination is described as consonant lengthening, and in the otjer as consonant doubling.Gemination wrote:Lengthened fricatives, nasals, laterals, approximants, and trills are simply prolonged. In lengthened stops, the obstruction of the airway is prolonged, delaying release. That is, the "hold" is lengthened. Long consonants are usually around one and a half or two times as long as short consonants, depending on the language.
In Ancient Greek, consonant length was distinctive, e.g., μέλω [mélɔː] "I am of interest" vs. μέλλω [mélːɔː] "I am going to". The distinction has been lost in Standard Modern Greek and most varieties, with the exception of Cypriot such as in the pairs πολλοί [polˈli] 'a lot' vs. πολύ [poˈli] 'very'; the same is true for some varieties of the Aegean.
Fair enough, if it existed in Koine Greek, I want to work towards having it in my pronunciation too. The question begging from the discrepency in descriptions is;
Which type of gemination should I be trying to work towards in my pronunciation of Koine Greek?