The present invention relates to a process for making a crystalline metallosilicate composition and comprising crystallites having an inner part (the core) and an outer part (the outer layer or shell) such that:the ratio Si / 
Metal is higher in the outer part than in the inner part,the crystallites have a continuous distribution of 
metal and 
silicon over the crystalline cross-section,said process comprising:a) providing an 
aqueous medium comprising OH− anions and a 
metal source,b) providing an 
aqueous medium comprising an inorganic source of 
silicon and optionally a templating agent,c) optionally providing a non aqueous 
liquid medium comprising optionally an organic source of silica,d) mixing the medium a), b) and the optional c) at conditions effective to partly crystallize the desired metallosilicate,e) 
cooling down the reaction mixture a)+b)+c) to about 
room temperature,f) decreasing the pH of the reaction mixture by at least 0.1 preferably by 0.3 to 4, more preferably by 0.5 to 3,g) subjecting the resulting mixture of step f) at conditions effective to continue the 
crystallization of the desired metallosilicate,h) recovering the desired metallosilicate,wherein at step d) in the mixture a)+b)+c), before 
crystallization,the ratio Si org / Si inorganic is <0.3, advantageously <0.2 and preferably 0,the 
molar ratio OH− / SiO2 is at least 0.3, advantageously from 0.3 to 0.62, preferably from 0.31 to 0.61, more preferably from 0.32 to 0.61, very preferably from 0.33 to 0.6.